diff --git a/backend-node/src/controllers/adminController.ts b/backend-node/src/controllers/adminController.ts
index 97dcab9d..72dc368a 100644
--- a/backend-node/src/controllers/adminController.ts
+++ b/backend-node/src/controllers/adminController.ts
@@ -2744,6 +2744,30 @@ export const saveUser = async (req: AuthenticatedRequest, res: Response) => {
       return;
     }
 
+    // 🔒 신규 등록(POST) 시 user_id 중복 체크 (타 회사 계정 덮어쓰기 방지)
+    if (!isUpdate) {
+      const existingById = await queryOne<{ user_id: string; company_code: string; user_name: string }>(
+        `SELECT user_id, company_code, user_name FROM user_info WHERE user_id = $1`,
+        [userData.userId]
+      );
+      if (existingById) {
+        logger.warn(`신규 사용자 등록 차단 - 이미 존재하는 user_id`, {
+          userId: userData.userId,
+          existingCompany: existingById.company_code,
+          requestCompany: userData.companyCode,
+        });
+        res.status(409).json({
+          success: false,
+          message: `이미 사용 중인 사용자 아이디입니다: ${userData.userId}`,
+          error: {
+            code: "DUPLICATE_USER_ID",
+            details: `user_id '${userData.userId}' already exists (company: ${existingById.company_code})`,
+          },
+        });
+        return;
+      }
+    }
+
     // 비밀번호 암호화 (비밀번호가 제공된 경우에만)
     let encryptedPassword = null;
     if (userData.userPassword) {
@@ -4161,11 +4185,31 @@ export const saveUserWithDept = async (
 
     // 1. 기존 사용자 확인
     const existingUser = await client.query(
-      "SELECT user_id FROM user_info WHERE user_id = $1",
+      "SELECT user_id, company_code FROM user_info WHERE user_id = $1",
       [userInfo.user_id]
     );
     const isExistingUser = existingUser.rows.length > 0;
 
+    // 🔒 신규 등록(isUpdate=false) 요청인데 이미 존재하면 중복 차단 (타 회사 계정 덮어쓰기 방지)
+    if (!isUpdate && isExistingUser) {
+      await client.query("ROLLBACK");
+      const existingCompany = existingUser.rows[0]?.company_code;
+      logger.warn(`신규 사용자(+부서) 등록 차단 - 이미 존재하는 user_id`, {
+        userId: userInfo.user_id,
+        existingCompany,
+        requestCompany: companyCode,
+      });
+      res.status(409).json({
+        success: false,
+        message: `이미 사용 중인 사용자 아이디입니다: ${userInfo.user_id}`,
+        error: {
+          code: "DUPLICATE_USER_ID",
+          details: `user_id '${userInfo.user_id}' already exists (company: ${existingCompany})`,
+        },
+      });
+      return;
+    }
+
     // 2. 비밀번호 암호화 (새 사용자이거나 비밀번호가 제공된 경우)
     let encryptedPassword = null;
     if (userInfo.user_password) {
diff --git a/backend-node/src/controllers/packagingController.ts b/backend-node/src/controllers/packagingController.ts
index 4974c80f..d87c0c7e 100644
--- a/backend-node/src/controllers/packagingController.ts
+++ b/backend-node/src/controllers/packagingController.ts
@@ -45,7 +45,7 @@ export async function createPkgUnit(
     const {
       pkg_code, pkg_name, pkg_type, status,
       width_mm, length_mm, height_mm,
-      self_weight_kg, max_load_kg, volume_l, remarks,
+      self_weight_kg, max_load_kg, volume_l, remarks, item_number,
     } = req.body;
 
     if (!pkg_code || !pkg_name) {
@@ -64,12 +64,12 @@ export async function createPkgUnit(
 
     const result = await pool.query(
       `INSERT INTO pkg_unit
-        (company_code, pkg_code, pkg_name, pkg_type, status,
-         width_mm, length_mm, height_mm, self_weight_kg, max_load_kg, volume_l, remarks, writer)
-       VALUES ($1,$2,$3,$4,$5,$6,$7,$8,$9,$10,$11,$12,$13)
+        (id, company_code, pkg_code, pkg_name, pkg_type, status,
+         width_mm, length_mm, height_mm, self_weight_kg, max_load_kg, volume_l, remarks, item_number, writer, created_date)
+       VALUES (gen_random_uuid()::text, $1,$2,$3,$4,$5,$6,$7,$8,$9,$10,$11,$12,$13,$14, NOW())
        RETURNING *`,
       [companyCode, pkg_code, pkg_name, pkg_type, status || "ACTIVE",
-       width_mm, length_mm, height_mm, self_weight_kg, max_load_kg, volume_l, remarks,
+       width_mm, length_mm, height_mm, self_weight_kg, max_load_kg, volume_l, remarks, item_number || pkg_code,
        req.user!.userId]
     );
 
@@ -92,7 +92,7 @@ export async function updatePkgUnit(
     const {
       pkg_name, pkg_type, status,
       width_mm, length_mm, height_mm,
-      self_weight_kg, max_load_kg, volume_l, remarks,
+      self_weight_kg, max_load_kg, volume_l, remarks, item_number,
     } = req.body;
 
     const result = await pool.query(
@@ -100,12 +100,14 @@ export async function updatePkgUnit(
         pkg_name=$1, pkg_type=$2, status=$3,
         width_mm=$4, length_mm=$5, height_mm=$6,
         self_weight_kg=$7, max_load_kg=$8, volume_l=$9, remarks=$10,
-        updated_date=NOW(), writer=$11
-       WHERE id=$12 AND company_code=$13
+        item_number=COALESCE($11, item_number),
+        updated_date=NOW(), writer=$12
+       WHERE id=$13 AND company_code=$14
        RETURNING *`,
       [pkg_name, pkg_type, status,
        width_mm, length_mm, height_mm,
        self_weight_kg, max_load_kg, volume_l, remarks,
+       item_number,
        req.user!.userId, id, companyCode]
     );
 
@@ -286,7 +288,7 @@ export async function createLoadingUnit(
     const {
       loading_code, loading_name, loading_type, status,
       width_mm, length_mm, height_mm,
-      self_weight_kg, max_load_kg, max_stack, remarks,
+      self_weight_kg, max_load_kg, max_stack, remarks, item_number,
     } = req.body;
 
     if (!loading_code || !loading_name) {
@@ -305,12 +307,12 @@ export async function createLoadingUnit(
 
     const result = await pool.query(
       `INSERT INTO loading_unit
-        (company_code, loading_code, loading_name, loading_type, status,
-         width_mm, length_mm, height_mm, self_weight_kg, max_load_kg, max_stack, remarks, writer)
-       VALUES ($1,$2,$3,$4,$5,$6,$7,$8,$9,$10,$11,$12,$13)
+        (id, company_code, loading_code, loading_name, loading_type, status,
+         width_mm, length_mm, height_mm, self_weight_kg, max_load_kg, max_stack, remarks, item_number, writer, created_date)
+       VALUES (gen_random_uuid()::text, $1,$2,$3,$4,$5,$6,$7,$8,$9,$10,$11,$12,$13,$14, NOW())
        RETURNING *`,
       [companyCode, loading_code, loading_name, loading_type, status || "ACTIVE",
-       width_mm, length_mm, height_mm, self_weight_kg, max_load_kg, max_stack, remarks,
+       width_mm, length_mm, height_mm, self_weight_kg, max_load_kg, max_stack, remarks, item_number || loading_code,
        req.user!.userId]
     );
 
@@ -333,7 +335,7 @@ export async function updateLoadingUnit(
     const {
       loading_name, loading_type, status,
       width_mm, length_mm, height_mm,
-      self_weight_kg, max_load_kg, max_stack, remarks,
+      self_weight_kg, max_load_kg, max_stack, remarks, item_number,
     } = req.body;
 
     const result = await pool.query(
@@ -341,12 +343,14 @@ export async function updateLoadingUnit(
         loading_name=$1, loading_type=$2, status=$3,
         width_mm=$4, length_mm=$5, height_mm=$6,
         self_weight_kg=$7, max_load_kg=$8, max_stack=$9, remarks=$10,
-        updated_date=NOW(), writer=$11
-       WHERE id=$12 AND company_code=$13
+        item_number=COALESCE($11, item_number),
+        updated_date=NOW(), writer=$12
+       WHERE id=$13 AND company_code=$14
        RETURNING *`,
       [loading_name, loading_type, status,
        width_mm, length_mm, height_mm,
        self_weight_kg, max_load_kg, max_stack, remarks,
+       item_number,
        req.user!.userId, id, companyCode]
     );
 
diff --git a/backend-node/src/controllers/tableManagementController.ts b/backend-node/src/controllers/tableManagementController.ts
index 24ad771d..2028dbb8 100644
--- a/backend-node/src/controllers/tableManagementController.ts
+++ b/backend-node/src/controllers/tableManagementController.ts
@@ -949,14 +949,25 @@ export async function addTableData(
 
     const tableManagementService = new TableManagementService();
 
-    // 🆕 멀티테넌시: company_code 자동 추가 (테이블에 company_code 컬럼이 있는 경우)
+    // 🆕 멀티테넌시: company_code 강제 설정 (테이블에 company_code 컬럼이 있는 경우)
+    // 일반 관리자는 자신의 company_code로 강제, 슈퍼관리자(*)는 클라이언트 값 허용(프리뷰용)
     const companyCode = req.user?.companyCode;
-    if (companyCode && !data.company_code) {
-      // 테이블에 company_code 컬럼이 있는지 확인
+    if (companyCode) {
       const hasCompanyCodeColumn = await tableManagementService.hasColumn(tableName, "company_code");
       if (hasCompanyCodeColumn) {
-        data.company_code = companyCode;
-        logger.info(`멀티테넌시: company_code 자동 추가 - ${companyCode}`);
+        if (companyCode === "*") {
+          // 슈퍼관리자: 클라이언트가 보낸 company_code 허용, 없으면 '*'
+          if (!data.company_code) {
+            data.company_code = companyCode;
+            logger.info(`멀티테넌시: company_code 자동 추가 - ${companyCode}`);
+          }
+        } else {
+          // 일반 관리자: 항상 자신의 company_code로 강제 (타 회사 주입 방지)
+          if (data.company_code && data.company_code !== companyCode) {
+            logger.warn(`멀티테넌시: 타 회사 company_code 주입 시도 차단 - 요청값: ${data.company_code}, 강제값: ${companyCode}`);
+          }
+          data.company_code = companyCode;
+        }
       }
     }
 
@@ -1115,6 +1126,37 @@ export async function editTableData(
     const tableManagementService = new TableManagementService();
     const companyCode = req.user?.companyCode || "*";
 
+    // 🔒 멀티테넌시 보안: 일반 관리자는 타 회사 데이터 수정 불가 + company_code 변경 차단
+    if (companyCode !== "*") {
+      const hasCompanyCodeColumn = await tableManagementService.hasColumn(tableName, "company_code");
+      if (hasCompanyCodeColumn) {
+        // 1. 원본 데이터의 company_code 확인
+        if (originalData?.id) {
+          try {
+            const existing = await tableManagementService.getTableData(tableName, {
+              page: 1, size: 1,
+              search: { id: String(originalData.id) },
+            });
+            const existingRow = existing.data?.[0];
+            if (existingRow && existingRow.company_code && existingRow.company_code !== companyCode && existingRow.company_code !== "*") {
+              logger.warn(`🔒 타 회사 데이터 수정 차단: ${tableName} id=${originalData.id}, 요청자=${companyCode}, 데이터소속=${existingRow.company_code}`);
+              res.status(403).json({
+                success: false,
+                message: "해당 데이터를 수정할 권한이 없습니다.",
+                error: { code: "FORBIDDEN_COMPANY", details: "cross-company edit blocked" },
+              });
+              return;
+            }
+          } catch { /* skip 검증 실패 시 원래 흐름 진행 */ }
+        }
+        // 2. updatedData에 company_code 변경 시도가 있으면 제거
+        if (updatedData.company_code && updatedData.company_code !== companyCode) {
+          logger.warn(`🔒 company_code 변경 시도 차단: ${tableName}, 요청값=${updatedData.company_code}`);
+          delete updatedData.company_code;
+        }
+      }
+    }
+
     // 회사별 NOT NULL 소프트 제약조건 검증 (수정 데이터 대상)
     const notNullViolations = await tableManagementService.validateNotNullConstraints(
       tableName,
diff --git a/backend-node/src/services/numberingRuleService.ts b/backend-node/src/services/numberingRuleService.ts
index 1179edbe..c1573d77 100644
--- a/backend-node/src/services/numberingRuleService.ts
+++ b/backend-node/src/services/numberingRuleService.ts
@@ -502,7 +502,8 @@ class NumberingRuleService {
 
     let baseSequence = currentCounter;
 
-    // 2. 규칙에 tableName/columnName이 설정되어 있으면 대상 테이블에서 MAX 조회
+    // 2. 규칙에 tableName/columnName이 설정되어 있으면 대상 테이블에서 MAX만 사용 (순수 MAX+1 방식)
+    //    - 삭제된 번호 재사용 가능 (카운터 값 무시)
     if (rule.tableName && rule.columnName) {
       try {
         const sortedParts = [...rule.parts].sort((a: any, b: any) => a.order - b.order);
@@ -515,12 +516,10 @@ class NumberingRuleService {
             psInfo.prefix, psInfo.suffix, psInfo.seqLength, companyCode
           );
 
-          if (maxFromTable > baseSequence) {
-            logger.info("테이블 내 최대값이 카운터보다 높음 → 동기화", {
-              ruleId, companyCode, currentCounter, maxFromTable,
-            });
-            baseSequence = maxFromTable;
-          }
+          logger.info("테이블 MAX 기준 채번", {
+            ruleId, companyCode, currentCounter, maxFromTable,
+          });
+          baseSequence = maxFromTable;
         }
       } catch (error: any) {
         logger.warn("테이블 기반 MAX 조회 실패, 카운터 기반 폴백", {
@@ -1422,7 +1421,7 @@ class NumberingRuleService {
       ? 0
       : await this.getSequenceForPrefix(pool, ruleId, companyCode, prefixKey);
 
-    // 대상 테이블에서 실제 최대 시퀀스 조회
+    // 대상 테이블에서 실제 최대 시퀀스만 사용 (순수 MAX+1)
     let baseSeq = currentSeq;
     if (rule.tableName && rule.columnName) {
       try {
@@ -1436,13 +1435,10 @@ class NumberingRuleService {
             psInfo.prefix, psInfo.suffix, psInfo.seqLength, companyCode
           );
 
-
-          if (maxFromTable > baseSeq) {
-            logger.info("미리보기: 테이블 내 최대값이 카운터보다 높음", {
-              ruleId, companyCode, currentSeq, maxFromTable,
-            });
-            baseSeq = maxFromTable;
-          }
+          logger.info("미리보기: 테이블 MAX 기준 채번", {
+            ruleId, companyCode, currentSeq, maxFromTable,
+          });
+          baseSeq = maxFromTable;
         }
       } catch (error: any) {
         logger.warn("미리보기: 테이블 기반 MAX 조회 실패, 카운터 기반 폴백", {
diff --git a/frontend/app/(main)/COMPANY_10/master-data/company/page.tsx b/frontend/app/(main)/COMPANY_10/master-data/company/page.tsx
index 9d7f2dea..0e4de0cd 100644
--- a/frontend/app/(main)/COMPANY_10/master-data/company/page.tsx
+++ b/frontend/app/(main)/COMPANY_10/master-data/company/page.tsx
@@ -167,6 +167,9 @@ export default function CompanyPage() {
   const [userEditMode, setUserEditMode] = useState(false);
   const [userForm, setUserForm] = useState<Record<string, any>>({});
   const [formErrors, setFormErrors] = useState<Record<string, string>>({});
+  // 사용자 ID 중복 확인 상태
+  const [idChecked, setIdChecked] = useState(false);
+  const [idChecking, setIdChecking] = useState(false);
 
   // 트리 구성
   const buildTree = (flatDepts: any[]): DeptNode[] => {
@@ -320,14 +323,39 @@ export default function CompanyPage() {
     if (editData) {
       setUserEditMode(true);
       setUserForm({ ...editData, user_password: "" });
+      setIdChecked(true);
     } else {
       setUserEditMode(false);
       setUserForm({ dept_code: selectedDeptCode || "", user_password: "" });
+      setIdChecked(false);
     }
     setFormErrors({});
     setUserModalOpen(true);
   };
 
+  // 사용자 ID 중복 확인
+  const handleCheckUserId = async () => {
+    const uid = (userForm.user_id || "").trim();
+    if (!uid) { toast.error("사용자 ID를 입력해주세요."); return; }
+    setIdChecking(true);
+    try {
+      const res = await apiClient.post("/admin/users/check-duplicate", { userId: uid });
+      const isDuplicate = res.data?.data?.isDuplicate;
+      if (isDuplicate) {
+        toast.error("이미 사용 중인 사용자 ID입니다.");
+        setIdChecked(false);
+      } else {
+        toast.success("사용 가능한 사용자 ID입니다.");
+        setIdChecked(true);
+      }
+    } catch {
+      toast.error("중복 확인에 실패했습니다.");
+      setIdChecked(false);
+    } finally {
+      setIdChecking(false);
+    }
+  };
+
   const handleUserFormChange = (field: string, value: string) => {
     const formatted = formatField(field, value);
     setUserForm((prev) => ({ ...prev, [field]: formatted }));
@@ -337,6 +365,7 @@ export default function CompanyPage() {
 
   const handleUserSave = async () => {
     if (!userForm.user_id) { toast.error("사용자 ID는 필수예요."); return; }
+    if (!userEditMode && !idChecked) { toast.error("사용자 ID 중복 확인을 해주세요."); return; }
     if (!userForm.user_name) { toast.error("사용자 이름은 필수예요."); return; }
     if (!userForm.dept_code) { toast.error("부서는 필수예요."); return; }
     const errors = validateForm(userForm, ["cell_phone", "email"]);
@@ -690,9 +719,31 @@ export default function CompanyPage() {
           </DialogHeader>
           <div className="grid grid-cols-2 gap-4 py-4">
             <div className="space-y-1.5">
-              <Label className="text-sm">사용자 ID <span className="text-destructive">*</span></Label>
-              <Input value={userForm.user_id || ""} onChange={(e) => setUserForm((p) => ({ ...p, user_id: e.target.value }))}
-                placeholder="사용자 ID" className="h-9" disabled={userEditMode} />
+              <Label className="text-sm">
+                사용자 ID <span className="text-destructive">*</span>
+                {!userEditMode && idChecked && (
+                  <span className="ml-2 text-[11px] font-semibold text-emerald-600">✓ 사용 가능</span>
+                )}
+              </Label>
+              <div className="flex gap-1.5">
+                <Input value={userForm.user_id || ""} onChange={(e) => {
+                    setUserForm((p) => ({ ...p, user_id: e.target.value }));
+                    if (!userEditMode) setIdChecked(false);
+                  }}
+                  placeholder="사용자 ID" className="h-9 flex-1" disabled={userEditMode} />
+                {!userEditMode && (
+                  <Button
+                    type="button"
+                    variant="outline"
+                    size="sm"
+                    className="h-9 shrink-0"
+                    onClick={handleCheckUserId}
+                    disabled={idChecking || !userForm.user_id}
+                  >
+                    {idChecking ? "확인중" : "중복확인"}
+                  </Button>
+                )}
+              </div>
             </div>
             <div className="space-y-1.5">
               <Label className="text-sm">이름 <span className="text-destructive">*</span></Label>
diff --git a/frontend/app/(main)/COMPANY_10/master-data/department/page.tsx b/frontend/app/(main)/COMPANY_10/master-data/department/page.tsx
index 23f70f2b..6eb4c2f2 100644
--- a/frontend/app/(main)/COMPANY_10/master-data/department/page.tsx
+++ b/frontend/app/(main)/COMPANY_10/master-data/department/page.tsx
@@ -80,6 +80,9 @@ export default function DepartmentPage() {
   const [userEditMode, setUserEditMode] = useState(false);
   const [userForm, setUserForm] = useState<Record<string, any>>({});
   const [formErrors, setFormErrors] = useState<Record<string, string>>({});
+  // 사용자 ID 중복 확인 상태
+  const [idChecked, setIdChecked] = useState(false);
+  const [idChecking, setIdChecking] = useState(false);
 
   // 사원 탭 (재직중/퇴사)
   const [memberTab, setMemberTab] = useState<"active" | "resigned">("active");
@@ -237,14 +240,39 @@ export default function DepartmentPage() {
     if (editData) {
       setUserEditMode(true);
       setUserForm({ ...editData, user_password: "" });
+      setIdChecked(true);
     } else {
       setUserEditMode(false);
       setUserForm({ dept_code: selectedDeptCode || "", user_password: "" });
+      setIdChecked(false);
     }
     setFormErrors({});
     setUserModalOpen(true);
   };
 
+  // 사용자 ID 중복 확인
+  const handleCheckUserId = async () => {
+    const uid = (userForm.user_id || "").trim();
+    if (!uid) { toast.error("사용자 ID를 입력해주세요."); return; }
+    setIdChecking(true);
+    try {
+      const res = await apiClient.post("/admin/users/check-duplicate", { userId: uid });
+      const isDuplicate = res.data?.data?.isDuplicate;
+      if (isDuplicate) {
+        toast.error("이미 사용 중인 사용자 ID입니다.");
+        setIdChecked(false);
+      } else {
+        toast.success("사용 가능한 사용자 ID입니다.");
+        setIdChecked(true);
+      }
+    } catch {
+      toast.error("중복 확인에 실패했습니다.");
+      setIdChecked(false);
+    } finally {
+      setIdChecking(false);
+    }
+  };
+
   const handleUserFormChange = (field: string, value: string) => {
     const formatted = formatField(field, value);
     setUserForm((prev) => ({ ...prev, [field]: formatted }));
@@ -254,6 +282,7 @@ export default function DepartmentPage() {
 
   const handleUserSave = async () => {
     if (!userForm.user_id) { toast.error("사용자 ID는 필수입니다."); return; }
+    if (!userEditMode && !idChecked) { toast.error("사용자 ID 중복 확인을 해주세요."); return; }
     if (!userForm.user_name) { toast.error("사용자 이름은 필수입니다."); return; }
     if (!userForm.dept_code) { toast.error("부서는 필수입니다."); return; }
     const errors = validateForm(userForm, ["cell_phone", "email"]);
@@ -633,14 +662,34 @@ export default function DepartmentPage() {
             <div className="space-y-1.5">
               <span className="block text-[11px] font-semibold uppercase tracking-wide text-muted-foreground">
                 사용자 ID <span className="text-destructive">*</span>
+                {!userEditMode && idChecked && (
+                  <span className="ml-2 text-[11px] font-semibold text-emerald-600">✓ 사용 가능</span>
+                )}
               </span>
-              <Input
-                value={userForm.user_id || ""}
-                onChange={(e) => setUserForm((p) => ({ ...p, user_id: e.target.value }))}
-                placeholder="사용자 ID를 입력해 주세요"
-                className="h-9"
-                disabled={userEditMode}
-              />
+              <div className="flex gap-1.5">
+                <Input
+                  value={userForm.user_id || ""}
+                  onChange={(e) => {
+                    setUserForm((p) => ({ ...p, user_id: e.target.value }));
+                    if (!userEditMode) setIdChecked(false);
+                  }}
+                  placeholder="사용자 ID를 입력해 주세요"
+                  className="h-9 flex-1"
+                  disabled={userEditMode}
+                />
+                {!userEditMode && (
+                  <Button
+                    type="button"
+                    variant="outline"
+                    size="sm"
+                    className="h-9 shrink-0"
+                    onClick={handleCheckUserId}
+                    disabled={idChecking || !userForm.user_id}
+                  >
+                    {idChecking ? "확인중" : "중복확인"}
+                  </Button>
+                )}
+              </div>
             </div>
             <div className="space-y-1.5">
               <span className="block text-[11px] font-semibold uppercase tracking-wide text-muted-foreground">
diff --git a/frontend/app/(main)/COMPANY_10/sales/customer/page.tsx b/frontend/app/(main)/COMPANY_10/sales/customer/page.tsx
index 33159c85..a2946e89 100644
--- a/frontend/app/(main)/COMPANY_10/sales/customer/page.tsx
+++ b/frontend/app/(main)/COMPANY_10/sales/customer/page.tsx
@@ -239,7 +239,7 @@ export default function CustomerManagementPage() {
       }));
 
       const res = await apiClient.post(`/table-management/tables/${CUSTOMER_TABLE}/data`, {
-        page: 1, size: 500,
+        page: 1, size: 99999,
         dataFilter: filters.length > 0 ? { enabled: true, filters } : undefined,
         autoFilter: true,
         sort: { columnName: "customer_code", order: "desc" },
diff --git a/frontend/app/(main)/COMPANY_10/sales/order/page.tsx b/frontend/app/(main)/COMPANY_10/sales/order/page.tsx
index 8f137c7a..76d6a061 100644
--- a/frontend/app/(main)/COMPANY_10/sales/order/page.tsx
+++ b/frontend/app/(main)/COMPANY_10/sales/order/page.tsx
@@ -1013,7 +1013,19 @@ export default function SalesOrderPage() {
                   </TableCell>
                 </TableRow>
               ) : (
-                filteredFlatRows.map((row) => {
+                ts.groupData(filteredFlatRows).map((row: any) => {
+                  // 그룹 요약 행 렌더링
+                  if (row._isGroupSummary) {
+                    return (
+                      <TableRow key={`summary-${row._groupKey || Math.random()}`} className="bg-muted/60 font-semibold border-t border-primary/20">
+                        <TableCell colSpan={TOTAL_COLS} className="py-2 px-3 text-[13px] text-primary">
+                          {row._groupLabel || "합계"}: {row._count ? `${row._count}건` : ""}
+                          {row.qty ? ` · 수량 ${Number(row.qty).toLocaleString()}` : ""}
+                          {row.amount ? ` · 금액 ${Number(row.amount).toLocaleString()}` : ""}
+                        </TableCell>
+                      </TableRow>
+                    );
+                  }
                   const isChecked = checkedIds.includes(row.id);
                   return (
                     <TableRow
diff --git a/frontend/app/(main)/COMPANY_16/master-data/company/page.tsx b/frontend/app/(main)/COMPANY_16/master-data/company/page.tsx
index 9d7f2dea..0e4de0cd 100644
--- a/frontend/app/(main)/COMPANY_16/master-data/company/page.tsx
+++ b/frontend/app/(main)/COMPANY_16/master-data/company/page.tsx
@@ -167,6 +167,9 @@ export default function CompanyPage() {
   const [userEditMode, setUserEditMode] = useState(false);
   const [userForm, setUserForm] = useState<Record<string, any>>({});
   const [formErrors, setFormErrors] = useState<Record<string, string>>({});
+  // 사용자 ID 중복 확인 상태
+  const [idChecked, setIdChecked] = useState(false);
+  const [idChecking, setIdChecking] = useState(false);
 
   // 트리 구성
   const buildTree = (flatDepts: any[]): DeptNode[] => {
@@ -320,14 +323,39 @@ export default function CompanyPage() {
     if (editData) {
       setUserEditMode(true);
       setUserForm({ ...editData, user_password: "" });
+      setIdChecked(true);
     } else {
       setUserEditMode(false);
       setUserForm({ dept_code: selectedDeptCode || "", user_password: "" });
+      setIdChecked(false);
     }
     setFormErrors({});
     setUserModalOpen(true);
   };
 
+  // 사용자 ID 중복 확인
+  const handleCheckUserId = async () => {
+    const uid = (userForm.user_id || "").trim();
+    if (!uid) { toast.error("사용자 ID를 입력해주세요."); return; }
+    setIdChecking(true);
+    try {
+      const res = await apiClient.post("/admin/users/check-duplicate", { userId: uid });
+      const isDuplicate = res.data?.data?.isDuplicate;
+      if (isDuplicate) {
+        toast.error("이미 사용 중인 사용자 ID입니다.");
+        setIdChecked(false);
+      } else {
+        toast.success("사용 가능한 사용자 ID입니다.");
+        setIdChecked(true);
+      }
+    } catch {
+      toast.error("중복 확인에 실패했습니다.");
+      setIdChecked(false);
+    } finally {
+      setIdChecking(false);
+    }
+  };
+
   const handleUserFormChange = (field: string, value: string) => {
     const formatted = formatField(field, value);
     setUserForm((prev) => ({ ...prev, [field]: formatted }));
@@ -337,6 +365,7 @@ export default function CompanyPage() {
 
   const handleUserSave = async () => {
     if (!userForm.user_id) { toast.error("사용자 ID는 필수예요."); return; }
+    if (!userEditMode && !idChecked) { toast.error("사용자 ID 중복 확인을 해주세요."); return; }
     if (!userForm.user_name) { toast.error("사용자 이름은 필수예요."); return; }
     if (!userForm.dept_code) { toast.error("부서는 필수예요."); return; }
     const errors = validateForm(userForm, ["cell_phone", "email"]);
@@ -690,9 +719,31 @@ export default function CompanyPage() {
           </DialogHeader>
           <div className="grid grid-cols-2 gap-4 py-4">
             <div className="space-y-1.5">
-              <Label className="text-sm">사용자 ID <span className="text-destructive">*</span></Label>
-              <Input value={userForm.user_id || ""} onChange={(e) => setUserForm((p) => ({ ...p, user_id: e.target.value }))}
-                placeholder="사용자 ID" className="h-9" disabled={userEditMode} />
+              <Label className="text-sm">
+                사용자 ID <span className="text-destructive">*</span>
+                {!userEditMode && idChecked && (
+                  <span className="ml-2 text-[11px] font-semibold text-emerald-600">✓ 사용 가능</span>
+                )}
+              </Label>
+              <div className="flex gap-1.5">
+                <Input value={userForm.user_id || ""} onChange={(e) => {
+                    setUserForm((p) => ({ ...p, user_id: e.target.value }));
+                    if (!userEditMode) setIdChecked(false);
+                  }}
+                  placeholder="사용자 ID" className="h-9 flex-1" disabled={userEditMode} />
+                {!userEditMode && (
+                  <Button
+                    type="button"
+                    variant="outline"
+                    size="sm"
+                    className="h-9 shrink-0"
+                    onClick={handleCheckUserId}
+                    disabled={idChecking || !userForm.user_id}
+                  >
+                    {idChecking ? "확인중" : "중복확인"}
+                  </Button>
+                )}
+              </div>
             </div>
             <div className="space-y-1.5">
               <Label className="text-sm">이름 <span className="text-destructive">*</span></Label>
diff --git a/frontend/app/(main)/COMPANY_16/master-data/department/page.tsx b/frontend/app/(main)/COMPANY_16/master-data/department/page.tsx
index 23f70f2b..33ea1535 100644
--- a/frontend/app/(main)/COMPANY_16/master-data/department/page.tsx
+++ b/frontend/app/(main)/COMPANY_16/master-data/department/page.tsx
@@ -79,6 +79,9 @@ export default function DepartmentPage() {
   const [userModalOpen, setUserModalOpen] = useState(false);
   const [userEditMode, setUserEditMode] = useState(false);
   const [userForm, setUserForm] = useState<Record<string, any>>({});
+  // 사용자 ID 중복 확인 상태 (true: 확인됨, false: 미확인/중복)
+  const [idChecked, setIdChecked] = useState(false);
+  const [idChecking, setIdChecking] = useState(false);
   const [formErrors, setFormErrors] = useState<Record<string, string>>({});
 
   // 사원 탭 (재직중/퇴사)
@@ -237,14 +240,39 @@ export default function DepartmentPage() {
     if (editData) {
       setUserEditMode(true);
       setUserForm({ ...editData, user_password: "" });
+      setIdChecked(true); // 수정 모드는 기존 ID 사용
     } else {
       setUserEditMode(false);
       setUserForm({ dept_code: selectedDeptCode || "", user_password: "" });
+      setIdChecked(false);
     }
     setFormErrors({});
     setUserModalOpen(true);
   };
 
+  // 사용자 ID 중복 확인
+  const handleCheckUserId = async () => {
+    const uid = (userForm.user_id || "").trim();
+    if (!uid) { toast.error("사용자 ID를 입력해주세요."); return; }
+    setIdChecking(true);
+    try {
+      const res = await apiClient.post("/admin/users/check-duplicate", { userId: uid });
+      const isDuplicate = res.data?.data?.isDuplicate;
+      if (isDuplicate) {
+        toast.error("이미 사용 중인 사용자 ID입니다.");
+        setIdChecked(false);
+      } else {
+        toast.success("사용 가능한 사용자 ID입니다.");
+        setIdChecked(true);
+      }
+    } catch {
+      toast.error("중복 확인에 실패했습니다.");
+      setIdChecked(false);
+    } finally {
+      setIdChecking(false);
+    }
+  };
+
   const handleUserFormChange = (field: string, value: string) => {
     const formatted = formatField(field, value);
     setUserForm((prev) => ({ ...prev, [field]: formatted }));
@@ -254,6 +282,7 @@ export default function DepartmentPage() {
 
   const handleUserSave = async () => {
     if (!userForm.user_id) { toast.error("사용자 ID는 필수입니다."); return; }
+    if (!userEditMode && !idChecked) { toast.error("사용자 ID 중복 확인을 해주세요."); return; }
     if (!userForm.user_name) { toast.error("사용자 이름은 필수입니다."); return; }
     if (!userForm.dept_code) { toast.error("부서는 필수입니다."); return; }
     const errors = validateForm(userForm, ["cell_phone", "email"]);
@@ -633,14 +662,34 @@ export default function DepartmentPage() {
             <div className="space-y-1.5">
               <span className="block text-[11px] font-semibold uppercase tracking-wide text-muted-foreground">
                 사용자 ID <span className="text-destructive">*</span>
+                {!userEditMode && idChecked && (
+                  <span className="ml-2 text-[11px] font-semibold text-emerald-600">✓ 사용 가능</span>
+                )}
               </span>
-              <Input
-                value={userForm.user_id || ""}
-                onChange={(e) => setUserForm((p) => ({ ...p, user_id: e.target.value }))}
-                placeholder="사용자 ID를 입력해 주세요"
-                className="h-9"
-                disabled={userEditMode}
-              />
+              <div className="flex gap-1.5">
+                <Input
+                  value={userForm.user_id || ""}
+                  onChange={(e) => {
+                    setUserForm((p) => ({ ...p, user_id: e.target.value }));
+                    if (!userEditMode) setIdChecked(false);
+                  }}
+                  placeholder="사용자 ID를 입력해 주세요"
+                  className="h-9 flex-1"
+                  disabled={userEditMode}
+                />
+                {!userEditMode && (
+                  <Button
+                    type="button"
+                    variant="outline"
+                    size="sm"
+                    className="h-9 shrink-0"
+                    onClick={handleCheckUserId}
+                    disabled={idChecking || !userForm.user_id}
+                  >
+                    {idChecking ? "확인중" : "중복확인"}
+                  </Button>
+                )}
+              </div>
             </div>
             <div className="space-y-1.5">
               <span className="block text-[11px] font-semibold uppercase tracking-wide text-muted-foreground">
diff --git a/frontend/app/(main)/COMPANY_16/sales/customer/page.tsx b/frontend/app/(main)/COMPANY_16/sales/customer/page.tsx
index 33159c85..a2946e89 100644
--- a/frontend/app/(main)/COMPANY_16/sales/customer/page.tsx
+++ b/frontend/app/(main)/COMPANY_16/sales/customer/page.tsx
@@ -239,7 +239,7 @@ export default function CustomerManagementPage() {
       }));
 
       const res = await apiClient.post(`/table-management/tables/${CUSTOMER_TABLE}/data`, {
-        page: 1, size: 500,
+        page: 1, size: 99999,
         dataFilter: filters.length > 0 ? { enabled: true, filters } : undefined,
         autoFilter: true,
         sort: { columnName: "customer_code", order: "desc" },
diff --git a/frontend/app/(main)/COMPANY_16/sales/order/page.tsx b/frontend/app/(main)/COMPANY_16/sales/order/page.tsx
index 8f137c7a..76d6a061 100644
--- a/frontend/app/(main)/COMPANY_16/sales/order/page.tsx
+++ b/frontend/app/(main)/COMPANY_16/sales/order/page.tsx
@@ -1013,7 +1013,19 @@ export default function SalesOrderPage() {
                   </TableCell>
                 </TableRow>
               ) : (
-                filteredFlatRows.map((row) => {
+                ts.groupData(filteredFlatRows).map((row: any) => {
+                  // 그룹 요약 행 렌더링
+                  if (row._isGroupSummary) {
+                    return (
+                      <TableRow key={`summary-${row._groupKey || Math.random()}`} className="bg-muted/60 font-semibold border-t border-primary/20">
+                        <TableCell colSpan={TOTAL_COLS} className="py-2 px-3 text-[13px] text-primary">
+                          {row._groupLabel || "합계"}: {row._count ? `${row._count}건` : ""}
+                          {row.qty ? ` · 수량 ${Number(row.qty).toLocaleString()}` : ""}
+                          {row.amount ? ` · 금액 ${Number(row.amount).toLocaleString()}` : ""}
+                        </TableCell>
+                      </TableRow>
+                    );
+                  }
                   const isChecked = checkedIds.includes(row.id);
                   return (
                     <TableRow
diff --git a/frontend/app/(main)/COMPANY_29/master-data/company/page.tsx b/frontend/app/(main)/COMPANY_29/master-data/company/page.tsx
index 9d7f2dea..0e4de0cd 100644
--- a/frontend/app/(main)/COMPANY_29/master-data/company/page.tsx
+++ b/frontend/app/(main)/COMPANY_29/master-data/company/page.tsx
@@ -167,6 +167,9 @@ export default function CompanyPage() {
   const [userEditMode, setUserEditMode] = useState(false);
   const [userForm, setUserForm] = useState<Record<string, any>>({});
   const [formErrors, setFormErrors] = useState<Record<string, string>>({});
+  // 사용자 ID 중복 확인 상태
+  const [idChecked, setIdChecked] = useState(false);
+  const [idChecking, setIdChecking] = useState(false);
 
   // 트리 구성
   const buildTree = (flatDepts: any[]): DeptNode[] => {
@@ -320,14 +323,39 @@ export default function CompanyPage() {
     if (editData) {
       setUserEditMode(true);
       setUserForm({ ...editData, user_password: "" });
+      setIdChecked(true);
     } else {
       setUserEditMode(false);
       setUserForm({ dept_code: selectedDeptCode || "", user_password: "" });
+      setIdChecked(false);
     }
     setFormErrors({});
     setUserModalOpen(true);
   };
 
+  // 사용자 ID 중복 확인
+  const handleCheckUserId = async () => {
+    const uid = (userForm.user_id || "").trim();
+    if (!uid) { toast.error("사용자 ID를 입력해주세요."); return; }
+    setIdChecking(true);
+    try {
+      const res = await apiClient.post("/admin/users/check-duplicate", { userId: uid });
+      const isDuplicate = res.data?.data?.isDuplicate;
+      if (isDuplicate) {
+        toast.error("이미 사용 중인 사용자 ID입니다.");
+        setIdChecked(false);
+      } else {
+        toast.success("사용 가능한 사용자 ID입니다.");
+        setIdChecked(true);
+      }
+    } catch {
+      toast.error("중복 확인에 실패했습니다.");
+      setIdChecked(false);
+    } finally {
+      setIdChecking(false);
+    }
+  };
+
   const handleUserFormChange = (field: string, value: string) => {
     const formatted = formatField(field, value);
     setUserForm((prev) => ({ ...prev, [field]: formatted }));
@@ -337,6 +365,7 @@ export default function CompanyPage() {
 
   const handleUserSave = async () => {
     if (!userForm.user_id) { toast.error("사용자 ID는 필수예요."); return; }
+    if (!userEditMode && !idChecked) { toast.error("사용자 ID 중복 확인을 해주세요."); return; }
     if (!userForm.user_name) { toast.error("사용자 이름은 필수예요."); return; }
     if (!userForm.dept_code) { toast.error("부서는 필수예요."); return; }
     const errors = validateForm(userForm, ["cell_phone", "email"]);
@@ -690,9 +719,31 @@ export default function CompanyPage() {
           </DialogHeader>
           <div className="grid grid-cols-2 gap-4 py-4">
             <div className="space-y-1.5">
-              <Label className="text-sm">사용자 ID <span className="text-destructive">*</span></Label>
-              <Input value={userForm.user_id || ""} onChange={(e) => setUserForm((p) => ({ ...p, user_id: e.target.value }))}
-                placeholder="사용자 ID" className="h-9" disabled={userEditMode} />
+              <Label className="text-sm">
+                사용자 ID <span className="text-destructive">*</span>
+                {!userEditMode && idChecked && (
+                  <span className="ml-2 text-[11px] font-semibold text-emerald-600">✓ 사용 가능</span>
+                )}
+              </Label>
+              <div className="flex gap-1.5">
+                <Input value={userForm.user_id || ""} onChange={(e) => {
+                    setUserForm((p) => ({ ...p, user_id: e.target.value }));
+                    if (!userEditMode) setIdChecked(false);
+                  }}
+                  placeholder="사용자 ID" className="h-9 flex-1" disabled={userEditMode} />
+                {!userEditMode && (
+                  <Button
+                    type="button"
+                    variant="outline"
+                    size="sm"
+                    className="h-9 shrink-0"
+                    onClick={handleCheckUserId}
+                    disabled={idChecking || !userForm.user_id}
+                  >
+                    {idChecking ? "확인중" : "중복확인"}
+                  </Button>
+                )}
+              </div>
             </div>
             <div className="space-y-1.5">
               <Label className="text-sm">이름 <span className="text-destructive">*</span></Label>
diff --git a/frontend/app/(main)/COMPANY_29/master-data/department/page.tsx b/frontend/app/(main)/COMPANY_29/master-data/department/page.tsx
index 23f70f2b..6eb4c2f2 100644
--- a/frontend/app/(main)/COMPANY_29/master-data/department/page.tsx
+++ b/frontend/app/(main)/COMPANY_29/master-data/department/page.tsx
@@ -80,6 +80,9 @@ export default function DepartmentPage() {
   const [userEditMode, setUserEditMode] = useState(false);
   const [userForm, setUserForm] = useState<Record<string, any>>({});
   const [formErrors, setFormErrors] = useState<Record<string, string>>({});
+  // 사용자 ID 중복 확인 상태
+  const [idChecked, setIdChecked] = useState(false);
+  const [idChecking, setIdChecking] = useState(false);
 
   // 사원 탭 (재직중/퇴사)
   const [memberTab, setMemberTab] = useState<"active" | "resigned">("active");
@@ -237,14 +240,39 @@ export default function DepartmentPage() {
     if (editData) {
       setUserEditMode(true);
       setUserForm({ ...editData, user_password: "" });
+      setIdChecked(true);
     } else {
       setUserEditMode(false);
       setUserForm({ dept_code: selectedDeptCode || "", user_password: "" });
+      setIdChecked(false);
     }
     setFormErrors({});
     setUserModalOpen(true);
   };
 
+  // 사용자 ID 중복 확인
+  const handleCheckUserId = async () => {
+    const uid = (userForm.user_id || "").trim();
+    if (!uid) { toast.error("사용자 ID를 입력해주세요."); return; }
+    setIdChecking(true);
+    try {
+      const res = await apiClient.post("/admin/users/check-duplicate", { userId: uid });
+      const isDuplicate = res.data?.data?.isDuplicate;
+      if (isDuplicate) {
+        toast.error("이미 사용 중인 사용자 ID입니다.");
+        setIdChecked(false);
+      } else {
+        toast.success("사용 가능한 사용자 ID입니다.");
+        setIdChecked(true);
+      }
+    } catch {
+      toast.error("중복 확인에 실패했습니다.");
+      setIdChecked(false);
+    } finally {
+      setIdChecking(false);
+    }
+  };
+
   const handleUserFormChange = (field: string, value: string) => {
     const formatted = formatField(field, value);
     setUserForm((prev) => ({ ...prev, [field]: formatted }));
@@ -254,6 +282,7 @@ export default function DepartmentPage() {
 
   const handleUserSave = async () => {
     if (!userForm.user_id) { toast.error("사용자 ID는 필수입니다."); return; }
+    if (!userEditMode && !idChecked) { toast.error("사용자 ID 중복 확인을 해주세요."); return; }
     if (!userForm.user_name) { toast.error("사용자 이름은 필수입니다."); return; }
     if (!userForm.dept_code) { toast.error("부서는 필수입니다."); return; }
     const errors = validateForm(userForm, ["cell_phone", "email"]);
@@ -633,14 +662,34 @@ export default function DepartmentPage() {
             <div className="space-y-1.5">
               <span className="block text-[11px] font-semibold uppercase tracking-wide text-muted-foreground">
                 사용자 ID <span className="text-destructive">*</span>
+                {!userEditMode && idChecked && (
+                  <span className="ml-2 text-[11px] font-semibold text-emerald-600">✓ 사용 가능</span>
+                )}
               </span>
-              <Input
-                value={userForm.user_id || ""}
-                onChange={(e) => setUserForm((p) => ({ ...p, user_id: e.target.value }))}
-                placeholder="사용자 ID를 입력해 주세요"
-                className="h-9"
-                disabled={userEditMode}
-              />
+              <div className="flex gap-1.5">
+                <Input
+                  value={userForm.user_id || ""}
+                  onChange={(e) => {
+                    setUserForm((p) => ({ ...p, user_id: e.target.value }));
+                    if (!userEditMode) setIdChecked(false);
+                  }}
+                  placeholder="사용자 ID를 입력해 주세요"
+                  className="h-9 flex-1"
+                  disabled={userEditMode}
+                />
+                {!userEditMode && (
+                  <Button
+                    type="button"
+                    variant="outline"
+                    size="sm"
+                    className="h-9 shrink-0"
+                    onClick={handleCheckUserId}
+                    disabled={idChecking || !userForm.user_id}
+                  >
+                    {idChecking ? "확인중" : "중복확인"}
+                  </Button>
+                )}
+              </div>
             </div>
             <div className="space-y-1.5">
               <span className="block text-[11px] font-semibold uppercase tracking-wide text-muted-foreground">
diff --git a/frontend/app/(main)/COMPANY_29/sales/customer/page.tsx b/frontend/app/(main)/COMPANY_29/sales/customer/page.tsx
index 33159c85..a2946e89 100644
--- a/frontend/app/(main)/COMPANY_29/sales/customer/page.tsx
+++ b/frontend/app/(main)/COMPANY_29/sales/customer/page.tsx
@@ -239,7 +239,7 @@ export default function CustomerManagementPage() {
       }));
 
       const res = await apiClient.post(`/table-management/tables/${CUSTOMER_TABLE}/data`, {
-        page: 1, size: 500,
+        page: 1, size: 99999,
         dataFilter: filters.length > 0 ? { enabled: true, filters } : undefined,
         autoFilter: true,
         sort: { columnName: "customer_code", order: "desc" },
diff --git a/frontend/app/(main)/COMPANY_29/sales/order/page.tsx b/frontend/app/(main)/COMPANY_29/sales/order/page.tsx
index 8f137c7a..76d6a061 100644
--- a/frontend/app/(main)/COMPANY_29/sales/order/page.tsx
+++ b/frontend/app/(main)/COMPANY_29/sales/order/page.tsx
@@ -1013,7 +1013,19 @@ export default function SalesOrderPage() {
                   </TableCell>
                 </TableRow>
               ) : (
-                filteredFlatRows.map((row) => {
+                ts.groupData(filteredFlatRows).map((row: any) => {
+                  // 그룹 요약 행 렌더링
+                  if (row._isGroupSummary) {
+                    return (
+                      <TableRow key={`summary-${row._groupKey || Math.random()}`} className="bg-muted/60 font-semibold border-t border-primary/20">
+                        <TableCell colSpan={TOTAL_COLS} className="py-2 px-3 text-[13px] text-primary">
+                          {row._groupLabel || "합계"}: {row._count ? `${row._count}건` : ""}
+                          {row.qty ? ` · 수량 ${Number(row.qty).toLocaleString()}` : ""}
+                          {row.amount ? ` · 금액 ${Number(row.amount).toLocaleString()}` : ""}
+                        </TableCell>
+                      </TableRow>
+                    );
+                  }
                   const isChecked = checkedIds.includes(row.id);
                   return (
                     <TableRow
diff --git a/frontend/app/(main)/COMPANY_30/master-data/company/page.tsx b/frontend/app/(main)/COMPANY_30/master-data/company/page.tsx
index 9d7f2dea..0e4de0cd 100644
--- a/frontend/app/(main)/COMPANY_30/master-data/company/page.tsx
+++ b/frontend/app/(main)/COMPANY_30/master-data/company/page.tsx
@@ -167,6 +167,9 @@ export default function CompanyPage() {
   const [userEditMode, setUserEditMode] = useState(false);
   const [userForm, setUserForm] = useState<Record<string, any>>({});
   const [formErrors, setFormErrors] = useState<Record<string, string>>({});
+  // 사용자 ID 중복 확인 상태
+  const [idChecked, setIdChecked] = useState(false);
+  const [idChecking, setIdChecking] = useState(false);
 
   // 트리 구성
   const buildTree = (flatDepts: any[]): DeptNode[] => {
@@ -320,14 +323,39 @@ export default function CompanyPage() {
     if (editData) {
       setUserEditMode(true);
       setUserForm({ ...editData, user_password: "" });
+      setIdChecked(true);
     } else {
       setUserEditMode(false);
       setUserForm({ dept_code: selectedDeptCode || "", user_password: "" });
+      setIdChecked(false);
     }
     setFormErrors({});
     setUserModalOpen(true);
   };
 
+  // 사용자 ID 중복 확인
+  const handleCheckUserId = async () => {
+    const uid = (userForm.user_id || "").trim();
+    if (!uid) { toast.error("사용자 ID를 입력해주세요."); return; }
+    setIdChecking(true);
+    try {
+      const res = await apiClient.post("/admin/users/check-duplicate", { userId: uid });
+      const isDuplicate = res.data?.data?.isDuplicate;
+      if (isDuplicate) {
+        toast.error("이미 사용 중인 사용자 ID입니다.");
+        setIdChecked(false);
+      } else {
+        toast.success("사용 가능한 사용자 ID입니다.");
+        setIdChecked(true);
+      }
+    } catch {
+      toast.error("중복 확인에 실패했습니다.");
+      setIdChecked(false);
+    } finally {
+      setIdChecking(false);
+    }
+  };
+
   const handleUserFormChange = (field: string, value: string) => {
     const formatted = formatField(field, value);
     setUserForm((prev) => ({ ...prev, [field]: formatted }));
@@ -337,6 +365,7 @@ export default function CompanyPage() {
 
   const handleUserSave = async () => {
     if (!userForm.user_id) { toast.error("사용자 ID는 필수예요."); return; }
+    if (!userEditMode && !idChecked) { toast.error("사용자 ID 중복 확인을 해주세요."); return; }
     if (!userForm.user_name) { toast.error("사용자 이름은 필수예요."); return; }
     if (!userForm.dept_code) { toast.error("부서는 필수예요."); return; }
     const errors = validateForm(userForm, ["cell_phone", "email"]);
@@ -690,9 +719,31 @@ export default function CompanyPage() {
           </DialogHeader>
           <div className="grid grid-cols-2 gap-4 py-4">
             <div className="space-y-1.5">
-              <Label className="text-sm">사용자 ID <span className="text-destructive">*</span></Label>
-              <Input value={userForm.user_id || ""} onChange={(e) => setUserForm((p) => ({ ...p, user_id: e.target.value }))}
-                placeholder="사용자 ID" className="h-9" disabled={userEditMode} />
+              <Label className="text-sm">
+                사용자 ID <span className="text-destructive">*</span>
+                {!userEditMode && idChecked && (
+                  <span className="ml-2 text-[11px] font-semibold text-emerald-600">✓ 사용 가능</span>
+                )}
+              </Label>
+              <div className="flex gap-1.5">
+                <Input value={userForm.user_id || ""} onChange={(e) => {
+                    setUserForm((p) => ({ ...p, user_id: e.target.value }));
+                    if (!userEditMode) setIdChecked(false);
+                  }}
+                  placeholder="사용자 ID" className="h-9 flex-1" disabled={userEditMode} />
+                {!userEditMode && (
+                  <Button
+                    type="button"
+                    variant="outline"
+                    size="sm"
+                    className="h-9 shrink-0"
+                    onClick={handleCheckUserId}
+                    disabled={idChecking || !userForm.user_id}
+                  >
+                    {idChecking ? "확인중" : "중복확인"}
+                  </Button>
+                )}
+              </div>
             </div>
             <div className="space-y-1.5">
               <Label className="text-sm">이름 <span className="text-destructive">*</span></Label>
diff --git a/frontend/app/(main)/COMPANY_30/master-data/department/page.tsx b/frontend/app/(main)/COMPANY_30/master-data/department/page.tsx
index 23f70f2b..6eb4c2f2 100644
--- a/frontend/app/(main)/COMPANY_30/master-data/department/page.tsx
+++ b/frontend/app/(main)/COMPANY_30/master-data/department/page.tsx
@@ -80,6 +80,9 @@ export default function DepartmentPage() {
   const [userEditMode, setUserEditMode] = useState(false);
   const [userForm, setUserForm] = useState<Record<string, any>>({});
   const [formErrors, setFormErrors] = useState<Record<string, string>>({});
+  // 사용자 ID 중복 확인 상태
+  const [idChecked, setIdChecked] = useState(false);
+  const [idChecking, setIdChecking] = useState(false);
 
   // 사원 탭 (재직중/퇴사)
   const [memberTab, setMemberTab] = useState<"active" | "resigned">("active");
@@ -237,14 +240,39 @@ export default function DepartmentPage() {
     if (editData) {
       setUserEditMode(true);
       setUserForm({ ...editData, user_password: "" });
+      setIdChecked(true);
     } else {
       setUserEditMode(false);
       setUserForm({ dept_code: selectedDeptCode || "", user_password: "" });
+      setIdChecked(false);
     }
     setFormErrors({});
     setUserModalOpen(true);
   };
 
+  // 사용자 ID 중복 확인
+  const handleCheckUserId = async () => {
+    const uid = (userForm.user_id || "").trim();
+    if (!uid) { toast.error("사용자 ID를 입력해주세요."); return; }
+    setIdChecking(true);
+    try {
+      const res = await apiClient.post("/admin/users/check-duplicate", { userId: uid });
+      const isDuplicate = res.data?.data?.isDuplicate;
+      if (isDuplicate) {
+        toast.error("이미 사용 중인 사용자 ID입니다.");
+        setIdChecked(false);
+      } else {
+        toast.success("사용 가능한 사용자 ID입니다.");
+        setIdChecked(true);
+      }
+    } catch {
+      toast.error("중복 확인에 실패했습니다.");
+      setIdChecked(false);
+    } finally {
+      setIdChecking(false);
+    }
+  };
+
   const handleUserFormChange = (field: string, value: string) => {
     const formatted = formatField(field, value);
     setUserForm((prev) => ({ ...prev, [field]: formatted }));
@@ -254,6 +282,7 @@ export default function DepartmentPage() {
 
   const handleUserSave = async () => {
     if (!userForm.user_id) { toast.error("사용자 ID는 필수입니다."); return; }
+    if (!userEditMode && !idChecked) { toast.error("사용자 ID 중복 확인을 해주세요."); return; }
     if (!userForm.user_name) { toast.error("사용자 이름은 필수입니다."); return; }
     if (!userForm.dept_code) { toast.error("부서는 필수입니다."); return; }
     const errors = validateForm(userForm, ["cell_phone", "email"]);
@@ -633,14 +662,34 @@ export default function DepartmentPage() {
             <div className="space-y-1.5">
               <span className="block text-[11px] font-semibold uppercase tracking-wide text-muted-foreground">
                 사용자 ID <span className="text-destructive">*</span>
+                {!userEditMode && idChecked && (
+                  <span className="ml-2 text-[11px] font-semibold text-emerald-600">✓ 사용 가능</span>
+                )}
               </span>
-              <Input
-                value={userForm.user_id || ""}
-                onChange={(e) => setUserForm((p) => ({ ...p, user_id: e.target.value }))}
-                placeholder="사용자 ID를 입력해 주세요"
-                className="h-9"
-                disabled={userEditMode}
-              />
+              <div className="flex gap-1.5">
+                <Input
+                  value={userForm.user_id || ""}
+                  onChange={(e) => {
+                    setUserForm((p) => ({ ...p, user_id: e.target.value }));
+                    if (!userEditMode) setIdChecked(false);
+                  }}
+                  placeholder="사용자 ID를 입력해 주세요"
+                  className="h-9 flex-1"
+                  disabled={userEditMode}
+                />
+                {!userEditMode && (
+                  <Button
+                    type="button"
+                    variant="outline"
+                    size="sm"
+                    className="h-9 shrink-0"
+                    onClick={handleCheckUserId}
+                    disabled={idChecking || !userForm.user_id}
+                  >
+                    {idChecking ? "확인중" : "중복확인"}
+                  </Button>
+                )}
+              </div>
             </div>
             <div className="space-y-1.5">
               <span className="block text-[11px] font-semibold uppercase tracking-wide text-muted-foreground">
diff --git a/frontend/app/(main)/COMPANY_30/sales/customer/page.tsx b/frontend/app/(main)/COMPANY_30/sales/customer/page.tsx
index 33159c85..a2946e89 100644
--- a/frontend/app/(main)/COMPANY_30/sales/customer/page.tsx
+++ b/frontend/app/(main)/COMPANY_30/sales/customer/page.tsx
@@ -239,7 +239,7 @@ export default function CustomerManagementPage() {
       }));
 
       const res = await apiClient.post(`/table-management/tables/${CUSTOMER_TABLE}/data`, {
-        page: 1, size: 500,
+        page: 1, size: 99999,
         dataFilter: filters.length > 0 ? { enabled: true, filters } : undefined,
         autoFilter: true,
         sort: { columnName: "customer_code", order: "desc" },
diff --git a/frontend/app/(main)/COMPANY_7/logistics/packaging/page.tsx b/frontend/app/(main)/COMPANY_7/logistics/packaging/page.tsx
index 6ae340aa..942002e3 100644
--- a/frontend/app/(main)/COMPANY_7/logistics/packaging/page.tsx
+++ b/frontend/app/(main)/COMPANY_7/logistics/packaging/page.tsx
@@ -37,7 +37,7 @@ const GRID_COLUMNS = [
   { key: "pkg_name", label: "포장명" },
   { key: "pkg_type", label: "유형" },
   { key: "size", label: "크기(mm)" },
-  { key: "max_weight", label: "최대중량" },
+  { key: "max_load_kg", label: "최대중량" },
   { key: "status", label: "상태" },
 ];
 
@@ -51,7 +51,7 @@ const LOADING_TYPE_LABEL: Record<string, string> = {
   ALU_PALLET: "알루미늄파렛트", CONTAINER: "컨테이너", STEEL_BOX: "철재함",
   CAGE: "케이지", ETC: "기타",
 };
-const STATUS_LABEL: Record<string, string> = { ACTIVE: "사용", INACTIVE: "미사용" };
+const STATUS_LABEL: Record<string, string> = { ACTIVE: "사용", INACTIVE: "미사용", UNREGISTERED: "미등록" };
 
 const getStatusColor = (s: string) => s === "ACTIVE" ? "bg-success/10 text-success" : "bg-muted text-muted-foreground";
 const fmtSize = (w: any, l: any, h: any) => {
@@ -118,20 +118,80 @@ export default function PackagingPage() {
 
   const [saving, setSaving] = useState(false);
 
-  // --- 데이터 로드 ---
+  // --- 데이터 로드 (item_info 기반 + pkg_unit/loading_unit LEFT JOIN 방식) ---
   const fetchPkgUnits = useCallback(async () => {
     setPkgLoading(true);
     try {
-      const res = await getPkgUnits();
-      if (res.success) setPkgUnits(res.data);
+      const [itemRes, pkgRes] = await Promise.all([
+        getItemsByDivision("포장재"),
+        getPkgUnits(),
+      ]);
+      const items = itemRes.success ? itemRes.data : [];
+      const existing = pkgRes.success ? pkgRes.data : [];
+      // item_info 기준으로 병합: item_number 매칭되는 pkg_unit이 있으면 그 데이터 사용, 없으면 미등록 placeholder
+      const merged: PkgUnit[] = items.map((item) => {
+        const match = existing.find((p) => p.item_number === item.item_number || p.pkg_code === item.item_number);
+        if (match) return { ...match, pkg_code: match.pkg_code || item.item_number, pkg_name: match.pkg_name || item.item_name };
+        const dims = parseSpecDimensions(item.size);
+        return {
+          id: "",
+          company_code: "",
+          pkg_code: item.item_number,
+          pkg_name: item.item_name,
+          pkg_type: "",
+          status: "INACTIVE",
+          width_mm: dims.w || null,
+          length_mm: dims.l || null,
+          height_mm: dims.h || null,
+          self_weight_kg: null,
+          max_load_kg: null,
+          volume_l: null,
+          remarks: null,
+          created_date: "",
+          writer: null,
+          item_number: item.item_number,
+        } as PkgUnit;
+      });
+      // 품목정보에 없지만 pkg_unit에만 있는 항목 (고아) 추가
+      const orphans = existing.filter((p) => !items.some((i) => i.item_number === p.item_number || i.item_number === p.pkg_code));
+      setPkgUnits([...merged, ...orphans]);
     } catch { /* ignore */ } finally { setPkgLoading(false); }
   }, []);
 
   const fetchLoadingUnits = useCallback(async () => {
     setLoadingLoading(true);
     try {
-      const res = await getLoadingUnits();
-      if (res.success) setLoadingUnits(res.data);
+      const [itemRes, luRes] = await Promise.all([
+        getItemsByDivision("적재함"),
+        getLoadingUnits(),
+      ]);
+      const items = itemRes.success ? itemRes.data : [];
+      const existing = luRes.success ? luRes.data : [];
+      const merged: LoadingUnit[] = items.map((item) => {
+        const match = existing.find((l) => l.item_number === item.item_number || l.loading_code === item.item_number);
+        if (match) return { ...match, loading_code: match.loading_code || item.item_number, loading_name: match.loading_name || item.item_name };
+        const dims = parseSpecDimensions(item.size);
+        return {
+          id: "",
+          company_code: "",
+          loading_code: item.item_number,
+          loading_name: item.item_name,
+          loading_type: "",
+          status: "INACTIVE",
+          width_mm: dims.w || null,
+          length_mm: dims.l || null,
+          height_mm: dims.h || null,
+          self_weight_kg: null,
+          max_load_kg: null,
+          max_stack: null,
+          remarks: null,
+          created_date: "",
+          writer: null,
+          item_number: item.item_number,
+        } as LoadingUnit;
+      });
+      const orphans = existing.filter((l) => !items.some((i) => i.item_number === l.item_number || i.item_number === l.loading_code));
+      setLoadingUnits([...merged, ...orphans]);
     } catch { /* ignore */ } finally { setLoadingLoading(false); }
   }, []);
 
@@ -177,12 +237,21 @@ export default function PackagingPage() {
   });
 
   // --- 포장재 등록/수정 모달 ---
-  const openPkgModal = async (mode: "create" | "edit") => {
-    setPkgModalMode(mode);
-    if (mode === "edit" && selectedPkg) {
-      setPkgForm({ ...selectedPkg });
+  // row: 리스트에서 클릭한 행. id가 빈 문자열이면 미등록 상태(item_info만 있음) → 등록 모달
+  const openPkgModal = async (mode: "create" | "edit", row?: PkgUnit) => {
+    const target = row || selectedPkg;
+    const isRegistered = !!(target && target.id);
+    const actualMode: "create" | "edit" = isRegistered ? "edit" : "create";
+    setPkgModalMode(actualMode);
+    if (target) {
+      // 기존 데이터 or 품목정보 기반 초기값 세팅
+      setPkgForm({
+        ...target,
+        status: target.status || "ACTIVE",
+        item_number: target.item_number || target.pkg_code || "",
+      });
     } else {
-      setPkgForm({ pkg_code: "", pkg_name: "", pkg_type: "", status: "ACTIVE", width_mm: "", length_mm: "", height_mm: "", self_weight_kg: "", max_load_kg: "", volume_l: "", remarks: "" });
+      setPkgForm({ pkg_code: "", pkg_name: "", pkg_type: "", status: "ACTIVE", width_mm: "", length_mm: "", height_mm: "", self_weight_kg: "", max_load_kg: "", volume_l: "", remarks: "", item_number: "" });
     }
     setPkgItemPopoverOpen(false);
     try {
@@ -232,12 +301,19 @@ export default function PackagingPage() {
   };
 
   // --- 적재함 등록/수정 모달 ---
-  const openLoadModal = async (mode: "create" | "edit") => {
-    setLoadModalMode(mode);
-    if (mode === "edit" && selectedLoading) {
-      setLoadForm({ ...selectedLoading });
+  const openLoadModal = async (mode: "create" | "edit", row?: LoadingUnit) => {
+    const target = row || selectedLoading;
+    const isRegistered = !!(target && target.id);
+    const actualMode: "create" | "edit" = isRegistered ? "edit" : "create";
+    setLoadModalMode(actualMode);
+    if (target) {
+      setLoadForm({
+        ...target,
+        status: target.status || "ACTIVE",
+        item_number: target.item_number || target.loading_code || "",
+      });
     } else {
-      setLoadForm({ loading_code: "", loading_name: "", loading_type: "", status: "ACTIVE", width_mm: "", length_mm: "", height_mm: "", self_weight_kg: "", max_load_kg: "", max_stack: "", remarks: "" });
+      setLoadForm({ loading_code: "", loading_name: "", loading_type: "", status: "ACTIVE", width_mm: "", length_mm: "", height_mm: "", self_weight_kg: "", max_load_kg: "", max_stack: "", remarks: "", item_number: "" });
     }
     setLoadItemPopoverOpen(false);
     try {
@@ -442,12 +518,8 @@ export default function PackagingPage() {
               <div className="h-4 w-px bg-border" />
             </>
           )}
-          <Button
-            size="sm"
-            onClick={() => activeTab === "packing" ? openPkgModal("create") : openLoadModal("create")}
-          >
-            <Plus className="mr-1 h-3.5 w-3.5" /> 등록
-          </Button>
+          {/* 메인 리스트가 품목정보 기반으로 자동 구성되므로 등록 버튼 제거.
+              미등록 상태의 품목을 직접 클릭하면 등록 모달이 열림. */}
           <Button variant="ghost" size="sm" onClick={() => ts.setOpen(true)} title="테이블 설정">
             <Settings2 className="h-4 w-4" />
           </Button>
@@ -466,22 +538,30 @@ export default function PackagingPage() {
                   size: { width: "w-[100px]", render: (_v: any, row: any) => fmtSize(row.width_mm, row.length_mm, row.height_mm) },
                   max_weight: { width: "w-[80px]", align: "right", render: (v: any) => Number(v || 0) > 0 ? `${v}kg` : "-" },
                   max_load_kg: { width: "w-[80px]", align: "right", render: (v: any) => Number(v || 0) > 0 ? `${v}kg` : "-" },
-                  status: { width: "w-[60px]", align: "center", render: (v: any) => (
-                    <span className={cn("rounded px-1.5 py-0.5 text-[10px] font-medium", getStatusColor(v))}>
-                      {STATUS_LABEL[v] || v}
-                    </span>
-                  )},
+                  status: { width: "w-[60px]", align: "center", render: (v: any, row: any) => {
+                    const isUnreg = !row.id;
+                    const cls = isUnreg ? "bg-warning/10 text-warning" : getStatusColor(v);
+                    const label = isUnreg ? "미등록" : (STATUS_LABEL[v] || v);
+                    return <span className={cn("rounded px-1.5 py-0.5 text-[10px] font-medium", cls)}>{label}</span>;
+                  }},
                 };
                 return { key: col.key, label: col.label, ...renderMap[col.key] };
               })}
               data={ts.groupData(filteredPkgUnits)}
-              rowKey={(row) => String(row.id)}
+              rowKey={(row) => row.id ? `reg-${row.id}` : `new-${row.pkg_code || row.item_number}`}
               loading={pkgLoading}
-              emptyMessage="등록된 포장재가 없어요"
-              selectedId={selectedPkg ? String(selectedPkg.id) : null}
+              emptyMessage="포장재 품목이 없어요. 품목정보에서 관리품목을 '포장재'로 등록해주세요."
+              selectedId={selectedPkg ? (selectedPkg.id ? `reg-${selectedPkg.id}` : `new-${selectedPkg.pkg_code || selectedPkg.item_number}`) : null}
               onSelect={(id) => {
-                const pkg = filteredPkgUnits.find((p) => String(p.id) === id);
-                if (pkg) selectPkg(pkg);
+                const pkg = filteredPkgUnits.find((p) => (p.id ? `reg-${p.id}` : `new-${p.pkg_code || p.item_number}`) === id);
+                if (pkg) {
+                  if (!pkg.id) {
+                    // 미등록 → 바로 등록 모달
+                    openPkgModal("create", pkg);
+                  } else {
+                    selectPkg(pkg);
+                  }
+                }
               }}
               showPagination={false}
               draggableColumns
@@ -592,14 +672,24 @@ export default function PackagingPage() {
                       </div>
                     </TableCell>
                   </TableRow>
-                ) : filteredLoadingUnits.map((l) => (
+                ) : filteredLoadingUnits.map((l) => {
+                  const isUnreg = !l.id;
+                  const rowKey = l.id ? `reg-${l.id}` : `new-${l.loading_code || l.item_number}`;
+                  const selKey = selectedLoading ? (selectedLoading.id ? `reg-${selectedLoading.id}` : `new-${selectedLoading.loading_code || selectedLoading.item_number}`) : null;
+                  return (
                   <TableRow
-                    key={l.id}
+                    key={rowKey}
                     className={cn(
                       "cursor-pointer text-xs transition-colors",
-                      selectedLoading?.id === l.id ? "bg-primary/5" : "hover:bg-muted/50"
+                      selKey === rowKey ? "bg-primary/5" : "hover:bg-muted/50"
                     )}
-                    onClick={() => selectLoading(l)}
+                    onClick={() => {
+                      if (isUnreg) {
+                        openLoadModal("create", l);
+                      } else {
+                        selectLoading(l);
+                      }
+                    }}
                   >
                     <TableCell className="p-2 font-medium">{l.loading_code}</TableCell>
                     <TableCell className="p-2">{l.loading_name}</TableCell>
@@ -607,12 +697,13 @@ export default function PackagingPage() {
                     <TableCell className="p-2 text-[10px] tabular-nums">{fmtSize(l.width_mm, l.length_mm, l.height_mm)}</TableCell>
                     <TableCell className="p-2 text-right">{Number(l.max_load_kg || 0) > 0 ? `${l.max_load_kg}kg` : "-"}</TableCell>
                     <TableCell className="p-2 text-center">
-                      <span className={cn("rounded px-1.5 py-0.5 text-[10px] font-medium", getStatusColor(l.status))}>
-                        {STATUS_LABEL[l.status] || l.status}
+                      <span className={cn("rounded px-1.5 py-0.5 text-[10px] font-medium", isUnreg ? "bg-warning/10 text-warning" : getStatusColor(l.status))}>
+                        {isUnreg ? "미등록" : (STATUS_LABEL[l.status] || l.status)}
                       </span>
                     </TableCell>
                   </TableRow>
-                ))}
+                  );
+                })}
               </TableBody>
             </Table>
           </div>
@@ -699,35 +790,9 @@ export default function PackagingPage() {
             {pkgModalMode === "create" && (
               <div className="rounded-lg border bg-muted/50 p-4">
                 <Label className="mb-2 block text-xs font-semibold">품목정보 연결 (구분: 포장재)</Label>
-                <Popover open={pkgItemPopoverOpen} onOpenChange={setPkgItemPopoverOpen}>
-                  <PopoverTrigger asChild>
-                    <Button variant="outline" role="combobox" className="h-9 w-full justify-between text-sm font-normal">
-                      {pkgForm.pkg_code ? `${pkgForm.pkg_name} (${pkgForm.pkg_code})` : "품목정보에서 포장재를 선택하세요"}
-                      <ChevronsUpDown className="ml-2 h-4 w-4 shrink-0 opacity-50" />
-                    </Button>
-                  </PopoverTrigger>
-                  <PopoverContent className="p-0" align="start" style={{ width: "var(--radix-popover-trigger-width)" }}>
-                    <Command filter={(value, search) => {
-                      const item = pkgItemOptions.find((i) => i.id === value);
-                      if (!item) return 0;
-                      const target = `${item.item_number} ${item.item_name} ${item.size || ""}`.toLowerCase();
-                      return target.includes(search.toLowerCase()) ? 1 : 0;
-                    }}>
-                      <CommandInput placeholder="품목코드 / 품목명 검색..." />
-                      <CommandList className="max-h-[200px]">
-                        <CommandEmpty>검색 결과가 없습니다</CommandEmpty>
-                        {pkgItemOptions.map((item) => (
-                          <CommandItem key={item.id} value={item.id} onSelect={() => onPkgItemSelect(item)} className="text-xs">
-                            <Check className={cn("mr-2 h-3 w-3", pkgForm.pkg_code === item.item_number ? "opacity-100" : "opacity-0")} />
-                            <span className="font-medium">{item.item_name}</span>
-                            <span className="ml-2 text-muted-foreground">{item.item_number}</span>
-                            {item.size && <span className="ml-auto text-[10px] text-muted-foreground">{item.size}</span>}
-                          </CommandItem>
-                        ))}
-                      </CommandList>
-                    </Command>
-                  </PopoverContent>
-                </Popover>
+                <div className="h-9 w-full rounded-md border border-input bg-muted px-3 py-2 text-sm text-muted-foreground flex items-center">
+                  {pkgForm.pkg_code ? `${pkgForm.pkg_name} (${pkgForm.pkg_code})` : "-"}
+                </div>
               </div>
             )}
             <div className="grid grid-cols-2 gap-4">
@@ -781,35 +846,9 @@ export default function PackagingPage() {
             {loadModalMode === "create" && (
               <div className="rounded-lg border bg-muted/50 p-4">
                 <Label className="mb-2 block text-xs font-semibold">품목정보 연결 (구분: 적재함)</Label>
-                <Popover open={loadItemPopoverOpen} onOpenChange={setLoadItemPopoverOpen}>
-                  <PopoverTrigger asChild>
-                    <Button variant="outline" role="combobox" className="h-9 w-full justify-between text-sm font-normal">
-                      {loadForm.loading_code ? `${loadForm.loading_name} (${loadForm.loading_code})` : "품목정보에서 적재함을 선택하세요"}
-                      <ChevronsUpDown className="ml-2 h-4 w-4 shrink-0 opacity-50" />
-                    </Button>
-                  </PopoverTrigger>
-                  <PopoverContent className="p-0" align="start" style={{ width: "var(--radix-popover-trigger-width)" }}>
-                    <Command filter={(value, search) => {
-                      const item = loadItemOptions.find((i) => i.id === value);
-                      if (!item) return 0;
-                      const target = `${item.item_number} ${item.item_name} ${item.size || ""}`.toLowerCase();
-                      return target.includes(search.toLowerCase()) ? 1 : 0;
-                    }}>
-                      <CommandInput placeholder="품목코드 / 품목명 검색..." />
-                      <CommandList className="max-h-[200px]">
-                        <CommandEmpty>검색 결과가 없습니다</CommandEmpty>
-                        {loadItemOptions.map((item) => (
-                          <CommandItem key={item.id} value={item.id} onSelect={() => onLoadItemSelect(item)} className="text-xs">
-                            <Check className={cn("mr-2 h-3 w-3", loadForm.loading_code === item.item_number ? "opacity-100" : "opacity-0")} />
-                            <span className="font-medium">{item.item_name}</span>
-                            <span className="ml-2 text-muted-foreground">{item.item_number}</span>
-                            {item.size && <span className="ml-auto text-[10px] text-muted-foreground">{item.size}</span>}
-                          </CommandItem>
-                        ))}
-                      </CommandList>
-                    </Command>
-                  </PopoverContent>
-                </Popover>
+                <div className="h-9 w-full rounded-md border border-input bg-muted px-3 py-2 text-sm text-muted-foreground flex items-center">
+                  {loadForm.loading_code ? `${loadForm.loading_name} (${loadForm.loading_code})` : "-"}
+                </div>
               </div>
             )}
             <div className="grid grid-cols-2 gap-4">
diff --git a/frontend/app/(main)/COMPANY_7/master-data/company/page.tsx b/frontend/app/(main)/COMPANY_7/master-data/company/page.tsx
index 9d7f2dea..0e4de0cd 100644
--- a/frontend/app/(main)/COMPANY_7/master-data/company/page.tsx
+++ b/frontend/app/(main)/COMPANY_7/master-data/company/page.tsx
@@ -167,6 +167,9 @@ export default function CompanyPage() {
   const [userEditMode, setUserEditMode] = useState(false);
   const [userForm, setUserForm] = useState<Record<string, any>>({});
   const [formErrors, setFormErrors] = useState<Record<string, string>>({});
+  // 사용자 ID 중복 확인 상태
+  const [idChecked, setIdChecked] = useState(false);
+  const [idChecking, setIdChecking] = useState(false);
 
   // 트리 구성
   const buildTree = (flatDepts: any[]): DeptNode[] => {
@@ -320,14 +323,39 @@ export default function CompanyPage() {
     if (editData) {
       setUserEditMode(true);
       setUserForm({ ...editData, user_password: "" });
+      setIdChecked(true);
     } else {
       setUserEditMode(false);
       setUserForm({ dept_code: selectedDeptCode || "", user_password: "" });
+      setIdChecked(false);
     }
     setFormErrors({});
     setUserModalOpen(true);
   };
 
+  // 사용자 ID 중복 확인
+  const handleCheckUserId = async () => {
+    const uid = (userForm.user_id || "").trim();
+    if (!uid) { toast.error("사용자 ID를 입력해주세요."); return; }
+    setIdChecking(true);
+    try {
+      const res = await apiClient.post("/admin/users/check-duplicate", { userId: uid });
+      const isDuplicate = res.data?.data?.isDuplicate;
+      if (isDuplicate) {
+        toast.error("이미 사용 중인 사용자 ID입니다.");
+        setIdChecked(false);
+      } else {
+        toast.success("사용 가능한 사용자 ID입니다.");
+        setIdChecked(true);
+      }
+    } catch {
+      toast.error("중복 확인에 실패했습니다.");
+      setIdChecked(false);
+    } finally {
+      setIdChecking(false);
+    }
+  };
+
   const handleUserFormChange = (field: string, value: string) => {
     const formatted = formatField(field, value);
     setUserForm((prev) => ({ ...prev, [field]: formatted }));
@@ -337,6 +365,7 @@ export default function CompanyPage() {
 
   const handleUserSave = async () => {
     if (!userForm.user_id) { toast.error("사용자 ID는 필수예요."); return; }
+    if (!userEditMode && !idChecked) { toast.error("사용자 ID 중복 확인을 해주세요."); return; }
     if (!userForm.user_name) { toast.error("사용자 이름은 필수예요."); return; }
     if (!userForm.dept_code) { toast.error("부서는 필수예요."); return; }
     const errors = validateForm(userForm, ["cell_phone", "email"]);
@@ -690,9 +719,31 @@ export default function CompanyPage() {
           </DialogHeader>
           <div className="grid grid-cols-2 gap-4 py-4">
             <div className="space-y-1.5">
-              <Label className="text-sm">사용자 ID <span className="text-destructive">*</span></Label>
-              <Input value={userForm.user_id || ""} onChange={(e) => setUserForm((p) => ({ ...p, user_id: e.target.value }))}
-                placeholder="사용자 ID" className="h-9" disabled={userEditMode} />
+              <Label className="text-sm">
+                사용자 ID <span className="text-destructive">*</span>
+                {!userEditMode && idChecked && (
+                  <span className="ml-2 text-[11px] font-semibold text-emerald-600">✓ 사용 가능</span>
+                )}
+              </Label>
+              <div className="flex gap-1.5">
+                <Input value={userForm.user_id || ""} onChange={(e) => {
+                    setUserForm((p) => ({ ...p, user_id: e.target.value }));
+                    if (!userEditMode) setIdChecked(false);
+                  }}
+                  placeholder="사용자 ID" className="h-9 flex-1" disabled={userEditMode} />
+                {!userEditMode && (
+                  <Button
+                    type="button"
+                    variant="outline"
+                    size="sm"
+                    className="h-9 shrink-0"
+                    onClick={handleCheckUserId}
+                    disabled={idChecking || !userForm.user_id}
+                  >
+                    {idChecking ? "확인중" : "중복확인"}
+                  </Button>
+                )}
+              </div>
             </div>
             <div className="space-y-1.5">
               <Label className="text-sm">이름 <span className="text-destructive">*</span></Label>
diff --git a/frontend/app/(main)/COMPANY_7/master-data/department/page.tsx b/frontend/app/(main)/COMPANY_7/master-data/department/page.tsx
index 23f70f2b..6eb4c2f2 100644
--- a/frontend/app/(main)/COMPANY_7/master-data/department/page.tsx
+++ b/frontend/app/(main)/COMPANY_7/master-data/department/page.tsx
@@ -80,6 +80,9 @@ export default function DepartmentPage() {
   const [userEditMode, setUserEditMode] = useState(false);
   const [userForm, setUserForm] = useState<Record<string, any>>({});
   const [formErrors, setFormErrors] = useState<Record<string, string>>({});
+  // 사용자 ID 중복 확인 상태
+  const [idChecked, setIdChecked] = useState(false);
+  const [idChecking, setIdChecking] = useState(false);
 
   // 사원 탭 (재직중/퇴사)
   const [memberTab, setMemberTab] = useState<"active" | "resigned">("active");
@@ -237,14 +240,39 @@ export default function DepartmentPage() {
     if (editData) {
       setUserEditMode(true);
       setUserForm({ ...editData, user_password: "" });
+      setIdChecked(true);
     } else {
       setUserEditMode(false);
       setUserForm({ dept_code: selectedDeptCode || "", user_password: "" });
+      setIdChecked(false);
     }
     setFormErrors({});
     setUserModalOpen(true);
   };
 
+  // 사용자 ID 중복 확인
+  const handleCheckUserId = async () => {
+    const uid = (userForm.user_id || "").trim();
+    if (!uid) { toast.error("사용자 ID를 입력해주세요."); return; }
+    setIdChecking(true);
+    try {
+      const res = await apiClient.post("/admin/users/check-duplicate", { userId: uid });
+      const isDuplicate = res.data?.data?.isDuplicate;
+      if (isDuplicate) {
+        toast.error("이미 사용 중인 사용자 ID입니다.");
+        setIdChecked(false);
+      } else {
+        toast.success("사용 가능한 사용자 ID입니다.");
+        setIdChecked(true);
+      }
+    } catch {
+      toast.error("중복 확인에 실패했습니다.");
+      setIdChecked(false);
+    } finally {
+      setIdChecking(false);
+    }
+  };
+
   const handleUserFormChange = (field: string, value: string) => {
     const formatted = formatField(field, value);
     setUserForm((prev) => ({ ...prev, [field]: formatted }));
@@ -254,6 +282,7 @@ export default function DepartmentPage() {
 
   const handleUserSave = async () => {
     if (!userForm.user_id) { toast.error("사용자 ID는 필수입니다."); return; }
+    if (!userEditMode && !idChecked) { toast.error("사용자 ID 중복 확인을 해주세요."); return; }
     if (!userForm.user_name) { toast.error("사용자 이름은 필수입니다."); return; }
     if (!userForm.dept_code) { toast.error("부서는 필수입니다."); return; }
     const errors = validateForm(userForm, ["cell_phone", "email"]);
@@ -633,14 +662,34 @@ export default function DepartmentPage() {
             <div className="space-y-1.5">
               <span className="block text-[11px] font-semibold uppercase tracking-wide text-muted-foreground">
                 사용자 ID <span className="text-destructive">*</span>
+                {!userEditMode && idChecked && (
+                  <span className="ml-2 text-[11px] font-semibold text-emerald-600">✓ 사용 가능</span>
+                )}
               </span>
-              <Input
-                value={userForm.user_id || ""}
-                onChange={(e) => setUserForm((p) => ({ ...p, user_id: e.target.value }))}
-                placeholder="사용자 ID를 입력해 주세요"
-                className="h-9"
-                disabled={userEditMode}
-              />
+              <div className="flex gap-1.5">
+                <Input
+                  value={userForm.user_id || ""}
+                  onChange={(e) => {
+                    setUserForm((p) => ({ ...p, user_id: e.target.value }));
+                    if (!userEditMode) setIdChecked(false);
+                  }}
+                  placeholder="사용자 ID를 입력해 주세요"
+                  className="h-9 flex-1"
+                  disabled={userEditMode}
+                />
+                {!userEditMode && (
+                  <Button
+                    type="button"
+                    variant="outline"
+                    size="sm"
+                    className="h-9 shrink-0"
+                    onClick={handleCheckUserId}
+                    disabled={idChecking || !userForm.user_id}
+                  >
+                    {idChecking ? "확인중" : "중복확인"}
+                  </Button>
+                )}
+              </div>
             </div>
             <div className="space-y-1.5">
               <span className="block text-[11px] font-semibold uppercase tracking-wide text-muted-foreground">
diff --git a/frontend/app/(main)/COMPANY_7/sales/customer/page.tsx b/frontend/app/(main)/COMPANY_7/sales/customer/page.tsx
index 33159c85..a2946e89 100644
--- a/frontend/app/(main)/COMPANY_7/sales/customer/page.tsx
+++ b/frontend/app/(main)/COMPANY_7/sales/customer/page.tsx
@@ -239,7 +239,7 @@ export default function CustomerManagementPage() {
       }));
 
       const res = await apiClient.post(`/table-management/tables/${CUSTOMER_TABLE}/data`, {
-        page: 1, size: 500,
+        page: 1, size: 99999,
         dataFilter: filters.length > 0 ? { enabled: true, filters } : undefined,
         autoFilter: true,
         sort: { columnName: "customer_code", order: "desc" },
diff --git a/frontend/app/(main)/COMPANY_7/sales/order/page.tsx b/frontend/app/(main)/COMPANY_7/sales/order/page.tsx
index 8f137c7a..76d6a061 100644
--- a/frontend/app/(main)/COMPANY_7/sales/order/page.tsx
+++ b/frontend/app/(main)/COMPANY_7/sales/order/page.tsx
@@ -1013,7 +1013,19 @@ export default function SalesOrderPage() {
                   </TableCell>
                 </TableRow>
               ) : (
-                filteredFlatRows.map((row) => {
+                ts.groupData(filteredFlatRows).map((row: any) => {
+                  // 그룹 요약 행 렌더링
+                  if (row._isGroupSummary) {
+                    return (
+                      <TableRow key={`summary-${row._groupKey || Math.random()}`} className="bg-muted/60 font-semibold border-t border-primary/20">
+                        <TableCell colSpan={TOTAL_COLS} className="py-2 px-3 text-[13px] text-primary">
+                          {row._groupLabel || "합계"}: {row._count ? `${row._count}건` : ""}
+                          {row.qty ? ` · 수량 ${Number(row.qty).toLocaleString()}` : ""}
+                          {row.amount ? ` · 금액 ${Number(row.amount).toLocaleString()}` : ""}
+                        </TableCell>
+                      </TableRow>
+                    );
+                  }
                   const isChecked = checkedIds.includes(row.id);
                   return (
                     <TableRow
diff --git a/frontend/app/(main)/COMPANY_8/master-data/company/page.tsx b/frontend/app/(main)/COMPANY_8/master-data/company/page.tsx
index 9d7f2dea..0e4de0cd 100644
--- a/frontend/app/(main)/COMPANY_8/master-data/company/page.tsx
+++ b/frontend/app/(main)/COMPANY_8/master-data/company/page.tsx
@@ -167,6 +167,9 @@ export default function CompanyPage() {
   const [userEditMode, setUserEditMode] = useState(false);
   const [userForm, setUserForm] = useState<Record<string, any>>({});
   const [formErrors, setFormErrors] = useState<Record<string, string>>({});
+  // 사용자 ID 중복 확인 상태
+  const [idChecked, setIdChecked] = useState(false);
+  const [idChecking, setIdChecking] = useState(false);
 
   // 트리 구성
   const buildTree = (flatDepts: any[]): DeptNode[] => {
@@ -320,14 +323,39 @@ export default function CompanyPage() {
     if (editData) {
       setUserEditMode(true);
       setUserForm({ ...editData, user_password: "" });
+      setIdChecked(true);
     } else {
       setUserEditMode(false);
       setUserForm({ dept_code: selectedDeptCode || "", user_password: "" });
+      setIdChecked(false);
     }
     setFormErrors({});
     setUserModalOpen(true);
   };
 
+  // 사용자 ID 중복 확인
+  const handleCheckUserId = async () => {
+    const uid = (userForm.user_id || "").trim();
+    if (!uid) { toast.error("사용자 ID를 입력해주세요."); return; }
+    setIdChecking(true);
+    try {
+      const res = await apiClient.post("/admin/users/check-duplicate", { userId: uid });
+      const isDuplicate = res.data?.data?.isDuplicate;
+      if (isDuplicate) {
+        toast.error("이미 사용 중인 사용자 ID입니다.");
+        setIdChecked(false);
+      } else {
+        toast.success("사용 가능한 사용자 ID입니다.");
+        setIdChecked(true);
+      }
+    } catch {
+      toast.error("중복 확인에 실패했습니다.");
+      setIdChecked(false);
+    } finally {
+      setIdChecking(false);
+    }
+  };
+
   const handleUserFormChange = (field: string, value: string) => {
     const formatted = formatField(field, value);
     setUserForm((prev) => ({ ...prev, [field]: formatted }));
@@ -337,6 +365,7 @@ export default function CompanyPage() {
 
   const handleUserSave = async () => {
     if (!userForm.user_id) { toast.error("사용자 ID는 필수예요."); return; }
+    if (!userEditMode && !idChecked) { toast.error("사용자 ID 중복 확인을 해주세요."); return; }
     if (!userForm.user_name) { toast.error("사용자 이름은 필수예요."); return; }
     if (!userForm.dept_code) { toast.error("부서는 필수예요."); return; }
     const errors = validateForm(userForm, ["cell_phone", "email"]);
@@ -690,9 +719,31 @@ export default function CompanyPage() {
           </DialogHeader>
           <div className="grid grid-cols-2 gap-4 py-4">
             <div className="space-y-1.5">
-              <Label className="text-sm">사용자 ID <span className="text-destructive">*</span></Label>
-              <Input value={userForm.user_id || ""} onChange={(e) => setUserForm((p) => ({ ...p, user_id: e.target.value }))}
-                placeholder="사용자 ID" className="h-9" disabled={userEditMode} />
+              <Label className="text-sm">
+                사용자 ID <span className="text-destructive">*</span>
+                {!userEditMode && idChecked && (
+                  <span className="ml-2 text-[11px] font-semibold text-emerald-600">✓ 사용 가능</span>
+                )}
+              </Label>
+              <div className="flex gap-1.5">
+                <Input value={userForm.user_id || ""} onChange={(e) => {
+                    setUserForm((p) => ({ ...p, user_id: e.target.value }));
+                    if (!userEditMode) setIdChecked(false);
+                  }}
+                  placeholder="사용자 ID" className="h-9 flex-1" disabled={userEditMode} />
+                {!userEditMode && (
+                  <Button
+                    type="button"
+                    variant="outline"
+                    size="sm"
+                    className="h-9 shrink-0"
+                    onClick={handleCheckUserId}
+                    disabled={idChecking || !userForm.user_id}
+                  >
+                    {idChecking ? "확인중" : "중복확인"}
+                  </Button>
+                )}
+              </div>
             </div>
             <div className="space-y-1.5">
               <Label className="text-sm">이름 <span className="text-destructive">*</span></Label>
diff --git a/frontend/app/(main)/COMPANY_8/master-data/department/page.tsx b/frontend/app/(main)/COMPANY_8/master-data/department/page.tsx
index 23f70f2b..6eb4c2f2 100644
--- a/frontend/app/(main)/COMPANY_8/master-data/department/page.tsx
+++ b/frontend/app/(main)/COMPANY_8/master-data/department/page.tsx
@@ -80,6 +80,9 @@ export default function DepartmentPage() {
   const [userEditMode, setUserEditMode] = useState(false);
   const [userForm, setUserForm] = useState<Record<string, any>>({});
   const [formErrors, setFormErrors] = useState<Record<string, string>>({});
+  // 사용자 ID 중복 확인 상태
+  const [idChecked, setIdChecked] = useState(false);
+  const [idChecking, setIdChecking] = useState(false);
 
   // 사원 탭 (재직중/퇴사)
   const [memberTab, setMemberTab] = useState<"active" | "resigned">("active");
@@ -237,14 +240,39 @@ export default function DepartmentPage() {
     if (editData) {
       setUserEditMode(true);
       setUserForm({ ...editData, user_password: "" });
+      setIdChecked(true);
     } else {
       setUserEditMode(false);
       setUserForm({ dept_code: selectedDeptCode || "", user_password: "" });
+      setIdChecked(false);
     }
     setFormErrors({});
     setUserModalOpen(true);
   };
 
+  // 사용자 ID 중복 확인
+  const handleCheckUserId = async () => {
+    const uid = (userForm.user_id || "").trim();
+    if (!uid) { toast.error("사용자 ID를 입력해주세요."); return; }
+    setIdChecking(true);
+    try {
+      const res = await apiClient.post("/admin/users/check-duplicate", { userId: uid });
+      const isDuplicate = res.data?.data?.isDuplicate;
+      if (isDuplicate) {
+        toast.error("이미 사용 중인 사용자 ID입니다.");
+        setIdChecked(false);
+      } else {
+        toast.success("사용 가능한 사용자 ID입니다.");
+        setIdChecked(true);
+      }
+    } catch {
+      toast.error("중복 확인에 실패했습니다.");
+      setIdChecked(false);
+    } finally {
+      setIdChecking(false);
+    }
+  };
+
   const handleUserFormChange = (field: string, value: string) => {
     const formatted = formatField(field, value);
     setUserForm((prev) => ({ ...prev, [field]: formatted }));
@@ -254,6 +282,7 @@ export default function DepartmentPage() {
 
   const handleUserSave = async () => {
     if (!userForm.user_id) { toast.error("사용자 ID는 필수입니다."); return; }
+    if (!userEditMode && !idChecked) { toast.error("사용자 ID 중복 확인을 해주세요."); return; }
     if (!userForm.user_name) { toast.error("사용자 이름은 필수입니다."); return; }
     if (!userForm.dept_code) { toast.error("부서는 필수입니다."); return; }
     const errors = validateForm(userForm, ["cell_phone", "email"]);
@@ -633,14 +662,34 @@ export default function DepartmentPage() {
             <div className="space-y-1.5">
               <span className="block text-[11px] font-semibold uppercase tracking-wide text-muted-foreground">
                 사용자 ID <span className="text-destructive">*</span>
+                {!userEditMode && idChecked && (
+                  <span className="ml-2 text-[11px] font-semibold text-emerald-600">✓ 사용 가능</span>
+                )}
               </span>
-              <Input
-                value={userForm.user_id || ""}
-                onChange={(e) => setUserForm((p) => ({ ...p, user_id: e.target.value }))}
-                placeholder="사용자 ID를 입력해 주세요"
-                className="h-9"
-                disabled={userEditMode}
-              />
+              <div className="flex gap-1.5">
+                <Input
+                  value={userForm.user_id || ""}
+                  onChange={(e) => {
+                    setUserForm((p) => ({ ...p, user_id: e.target.value }));
+                    if (!userEditMode) setIdChecked(false);
+                  }}
+                  placeholder="사용자 ID를 입력해 주세요"
+                  className="h-9 flex-1"
+                  disabled={userEditMode}
+                />
+                {!userEditMode && (
+                  <Button
+                    type="button"
+                    variant="outline"
+                    size="sm"
+                    className="h-9 shrink-0"
+                    onClick={handleCheckUserId}
+                    disabled={idChecking || !userForm.user_id}
+                  >
+                    {idChecking ? "확인중" : "중복확인"}
+                  </Button>
+                )}
+              </div>
             </div>
             <div className="space-y-1.5">
               <span className="block text-[11px] font-semibold uppercase tracking-wide text-muted-foreground">
diff --git a/frontend/app/(main)/COMPANY_8/sales/customer/page.tsx b/frontend/app/(main)/COMPANY_8/sales/customer/page.tsx
index 33159c85..a2946e89 100644
--- a/frontend/app/(main)/COMPANY_8/sales/customer/page.tsx
+++ b/frontend/app/(main)/COMPANY_8/sales/customer/page.tsx
@@ -239,7 +239,7 @@ export default function CustomerManagementPage() {
       }));
 
       const res = await apiClient.post(`/table-management/tables/${CUSTOMER_TABLE}/data`, {
-        page: 1, size: 500,
+        page: 1, size: 99999,
         dataFilter: filters.length > 0 ? { enabled: true, filters } : undefined,
         autoFilter: true,
         sort: { columnName: "customer_code", order: "desc" },
diff --git a/frontend/app/(main)/COMPANY_8/sales/order/page.tsx b/frontend/app/(main)/COMPANY_8/sales/order/page.tsx
index 8f137c7a..76d6a061 100644
--- a/frontend/app/(main)/COMPANY_8/sales/order/page.tsx
+++ b/frontend/app/(main)/COMPANY_8/sales/order/page.tsx
@@ -1013,7 +1013,19 @@ export default function SalesOrderPage() {
                   </TableCell>
                 </TableRow>
               ) : (
-                filteredFlatRows.map((row) => {
+                ts.groupData(filteredFlatRows).map((row: any) => {
+                  // 그룹 요약 행 렌더링
+                  if (row._isGroupSummary) {
+                    return (
+                      <TableRow key={`summary-${row._groupKey || Math.random()}`} className="bg-muted/60 font-semibold border-t border-primary/20">
+                        <TableCell colSpan={TOTAL_COLS} className="py-2 px-3 text-[13px] text-primary">
+                          {row._groupLabel || "합계"}: {row._count ? `${row._count}건` : ""}
+                          {row.qty ? ` · 수량 ${Number(row.qty).toLocaleString()}` : ""}
+                          {row.amount ? ` · 금액 ${Number(row.amount).toLocaleString()}` : ""}
+                        </TableCell>
+                      </TableRow>
+                    );
+                  }
                   const isChecked = checkedIds.includes(row.id);
                   return (
                     <TableRow
diff --git a/frontend/app/(main)/COMPANY_9/master-data/company/page.tsx b/frontend/app/(main)/COMPANY_9/master-data/company/page.tsx
index 9d7f2dea..0e4de0cd 100644
--- a/frontend/app/(main)/COMPANY_9/master-data/company/page.tsx
+++ b/frontend/app/(main)/COMPANY_9/master-data/company/page.tsx
@@ -167,6 +167,9 @@ export default function CompanyPage() {
   const [userEditMode, setUserEditMode] = useState(false);
   const [userForm, setUserForm] = useState<Record<string, any>>({});
   const [formErrors, setFormErrors] = useState<Record<string, string>>({});
+  // 사용자 ID 중복 확인 상태
+  const [idChecked, setIdChecked] = useState(false);
+  const [idChecking, setIdChecking] = useState(false);
 
   // 트리 구성
   const buildTree = (flatDepts: any[]): DeptNode[] => {
@@ -320,14 +323,39 @@ export default function CompanyPage() {
     if (editData) {
       setUserEditMode(true);
       setUserForm({ ...editData, user_password: "" });
+      setIdChecked(true);
     } else {
       setUserEditMode(false);
       setUserForm({ dept_code: selectedDeptCode || "", user_password: "" });
+      setIdChecked(false);
     }
     setFormErrors({});
     setUserModalOpen(true);
   };
 
+  // 사용자 ID 중복 확인
+  const handleCheckUserId = async () => {
+    const uid = (userForm.user_id || "").trim();
+    if (!uid) { toast.error("사용자 ID를 입력해주세요."); return; }
+    setIdChecking(true);
+    try {
+      const res = await apiClient.post("/admin/users/check-duplicate", { userId: uid });
+      const isDuplicate = res.data?.data?.isDuplicate;
+      if (isDuplicate) {
+        toast.error("이미 사용 중인 사용자 ID입니다.");
+        setIdChecked(false);
+      } else {
+        toast.success("사용 가능한 사용자 ID입니다.");
+        setIdChecked(true);
+      }
+    } catch {
+      toast.error("중복 확인에 실패했습니다.");
+      setIdChecked(false);
+    } finally {
+      setIdChecking(false);
+    }
+  };
+
   const handleUserFormChange = (field: string, value: string) => {
     const formatted = formatField(field, value);
     setUserForm((prev) => ({ ...prev, [field]: formatted }));
@@ -337,6 +365,7 @@ export default function CompanyPage() {
 
   const handleUserSave = async () => {
     if (!userForm.user_id) { toast.error("사용자 ID는 필수예요."); return; }
+    if (!userEditMode && !idChecked) { toast.error("사용자 ID 중복 확인을 해주세요."); return; }
     if (!userForm.user_name) { toast.error("사용자 이름은 필수예요."); return; }
     if (!userForm.dept_code) { toast.error("부서는 필수예요."); return; }
     const errors = validateForm(userForm, ["cell_phone", "email"]);
@@ -690,9 +719,31 @@ export default function CompanyPage() {
           </DialogHeader>
           <div className="grid grid-cols-2 gap-4 py-4">
             <div className="space-y-1.5">
-              <Label className="text-sm">사용자 ID <span className="text-destructive">*</span></Label>
-              <Input value={userForm.user_id || ""} onChange={(e) => setUserForm((p) => ({ ...p, user_id: e.target.value }))}
-                placeholder="사용자 ID" className="h-9" disabled={userEditMode} />
+              <Label className="text-sm">
+                사용자 ID <span className="text-destructive">*</span>
+                {!userEditMode && idChecked && (
+                  <span className="ml-2 text-[11px] font-semibold text-emerald-600">✓ 사용 가능</span>
+                )}
+              </Label>
+              <div className="flex gap-1.5">
+                <Input value={userForm.user_id || ""} onChange={(e) => {
+                    setUserForm((p) => ({ ...p, user_id: e.target.value }));
+                    if (!userEditMode) setIdChecked(false);
+                  }}
+                  placeholder="사용자 ID" className="h-9 flex-1" disabled={userEditMode} />
+                {!userEditMode && (
+                  <Button
+                    type="button"
+                    variant="outline"
+                    size="sm"
+                    className="h-9 shrink-0"
+                    onClick={handleCheckUserId}
+                    disabled={idChecking || !userForm.user_id}
+                  >
+                    {idChecking ? "확인중" : "중복확인"}
+                  </Button>
+                )}
+              </div>
             </div>
             <div className="space-y-1.5">
               <Label className="text-sm">이름 <span className="text-destructive">*</span></Label>
diff --git a/frontend/app/(main)/COMPANY_9/master-data/department/page.tsx b/frontend/app/(main)/COMPANY_9/master-data/department/page.tsx
index 23f70f2b..6eb4c2f2 100644
--- a/frontend/app/(main)/COMPANY_9/master-data/department/page.tsx
+++ b/frontend/app/(main)/COMPANY_9/master-data/department/page.tsx
@@ -80,6 +80,9 @@ export default function DepartmentPage() {
   const [userEditMode, setUserEditMode] = useState(false);
   const [userForm, setUserForm] = useState<Record<string, any>>({});
   const [formErrors, setFormErrors] = useState<Record<string, string>>({});
+  // 사용자 ID 중복 확인 상태
+  const [idChecked, setIdChecked] = useState(false);
+  const [idChecking, setIdChecking] = useState(false);
 
   // 사원 탭 (재직중/퇴사)
   const [memberTab, setMemberTab] = useState<"active" | "resigned">("active");
@@ -237,14 +240,39 @@ export default function DepartmentPage() {
     if (editData) {
       setUserEditMode(true);
       setUserForm({ ...editData, user_password: "" });
+      setIdChecked(true);
     } else {
       setUserEditMode(false);
       setUserForm({ dept_code: selectedDeptCode || "", user_password: "" });
+      setIdChecked(false);
     }
     setFormErrors({});
     setUserModalOpen(true);
   };
 
+  // 사용자 ID 중복 확인
+  const handleCheckUserId = async () => {
+    const uid = (userForm.user_id || "").trim();
+    if (!uid) { toast.error("사용자 ID를 입력해주세요."); return; }
+    setIdChecking(true);
+    try {
+      const res = await apiClient.post("/admin/users/check-duplicate", { userId: uid });
+      const isDuplicate = res.data?.data?.isDuplicate;
+      if (isDuplicate) {
+        toast.error("이미 사용 중인 사용자 ID입니다.");
+        setIdChecked(false);
+      } else {
+        toast.success("사용 가능한 사용자 ID입니다.");
+        setIdChecked(true);
+      }
+    } catch {
+      toast.error("중복 확인에 실패했습니다.");
+      setIdChecked(false);
+    } finally {
+      setIdChecking(false);
+    }
+  };
+
   const handleUserFormChange = (field: string, value: string) => {
     const formatted = formatField(field, value);
     setUserForm((prev) => ({ ...prev, [field]: formatted }));
@@ -254,6 +282,7 @@ export default function DepartmentPage() {
 
   const handleUserSave = async () => {
     if (!userForm.user_id) { toast.error("사용자 ID는 필수입니다."); return; }
+    if (!userEditMode && !idChecked) { toast.error("사용자 ID 중복 확인을 해주세요."); return; }
     if (!userForm.user_name) { toast.error("사용자 이름은 필수입니다."); return; }
     if (!userForm.dept_code) { toast.error("부서는 필수입니다."); return; }
     const errors = validateForm(userForm, ["cell_phone", "email"]);
@@ -633,14 +662,34 @@ export default function DepartmentPage() {
             <div className="space-y-1.5">
               <span className="block text-[11px] font-semibold uppercase tracking-wide text-muted-foreground">
                 사용자 ID <span className="text-destructive">*</span>
+                {!userEditMode && idChecked && (
+                  <span className="ml-2 text-[11px] font-semibold text-emerald-600">✓ 사용 가능</span>
+                )}
               </span>
-              <Input
-                value={userForm.user_id || ""}
-                onChange={(e) => setUserForm((p) => ({ ...p, user_id: e.target.value }))}
-                placeholder="사용자 ID를 입력해 주세요"
-                className="h-9"
-                disabled={userEditMode}
-              />
+              <div className="flex gap-1.5">
+                <Input
+                  value={userForm.user_id || ""}
+                  onChange={(e) => {
+                    setUserForm((p) => ({ ...p, user_id: e.target.value }));
+                    if (!userEditMode) setIdChecked(false);
+                  }}
+                  placeholder="사용자 ID를 입력해 주세요"
+                  className="h-9 flex-1"
+                  disabled={userEditMode}
+                />
+                {!userEditMode && (
+                  <Button
+                    type="button"
+                    variant="outline"
+                    size="sm"
+                    className="h-9 shrink-0"
+                    onClick={handleCheckUserId}
+                    disabled={idChecking || !userForm.user_id}
+                  >
+                    {idChecking ? "확인중" : "중복확인"}
+                  </Button>
+                )}
+              </div>
             </div>
             <div className="space-y-1.5">
               <span className="block text-[11px] font-semibold uppercase tracking-wide text-muted-foreground">
diff --git a/frontend/app/(main)/COMPANY_9/sales/customer/page.tsx b/frontend/app/(main)/COMPANY_9/sales/customer/page.tsx
index 33159c85..a2946e89 100644
--- a/frontend/app/(main)/COMPANY_9/sales/customer/page.tsx
+++ b/frontend/app/(main)/COMPANY_9/sales/customer/page.tsx
@@ -239,7 +239,7 @@ export default function CustomerManagementPage() {
       }));
 
       const res = await apiClient.post(`/table-management/tables/${CUSTOMER_TABLE}/data`, {
-        page: 1, size: 500,
+        page: 1, size: 99999,
         dataFilter: filters.length > 0 ? { enabled: true, filters } : undefined,
         autoFilter: true,
         sort: { columnName: "customer_code", order: "desc" },
diff --git a/frontend/lib/api/packaging.ts b/frontend/lib/api/packaging.ts
index 81c67d5f..016e7d49 100644
--- a/frontend/lib/api/packaging.ts
+++ b/frontend/lib/api/packaging.ts
@@ -18,6 +18,7 @@ export interface PkgUnit {
   remarks: string | null;
   created_date: string;
   writer: string | null;
+  item_number?: string | null;
 }
 
 export interface PkgUnitItem {
@@ -48,6 +49,7 @@ export interface LoadingUnit {
   remarks: string | null;
   created_date: string;
   writer: string | null;
+  item_number?: string | null;
 }
 
 export interface LoadingUnitPkg {