diff --git a/backend-node/src/routes/externalDbConnectionRoutes.ts b/backend-node/src/routes/externalDbConnectionRoutes.ts
index d008293c..950e6c25 100644
--- a/backend-node/src/routes/externalDbConnectionRoutes.ts
+++ b/backend-node/src/routes/externalDbConnectionRoutes.ts
@@ -262,7 +262,9 @@ router.post(
         });
       }
 
-      const result = await ExternalDbConnectionService.testConnectionById(id);
+      // 테스트용 비밀번호가 제공된 경우 사용
+      const testData = req.body.password ? { password: req.body.password } : undefined;
+      const result = await ExternalDbConnectionService.testConnectionById(id, testData);
 
       return res.status(200).json({
         success: result.success,
diff --git a/backend-node/src/services/externalDbConnectionService.ts b/backend-node/src/services/externalDbConnectionService.ts
index bd9f8e86..b41b9be7 100644
--- a/backend-node/src/services/externalDbConnectionService.ts
+++ b/backend-node/src/services/externalDbConnectionService.ts
@@ -239,13 +239,43 @@ export class ExternalDbConnectionService {
         }
       }
 
+      // 비밀번호가 변경되는 경우, 연결 테스트 먼저 수행
+      if (data.password && data.password !== "***ENCRYPTED***") {
+        // 임시 연결 설정으로 테스트
+        const testConfig = {
+          host: data.host || existingConnection.host,
+          port: data.port || existingConnection.port,
+          database: data.database_name || existingConnection.database_name,
+          user: data.username || existingConnection.username,
+          password: data.password, // 새로 입력된 비밀번호로 테스트
+          connectionTimeoutMillis: data.connection_timeout != null ? data.connection_timeout * 1000 : undefined,
+          queryTimeoutMillis: data.query_timeout != null ? data.query_timeout * 1000 : undefined,
+          ssl: (data.ssl_enabled || existingConnection.ssl_enabled) === "Y" ? { rejectUnauthorized: false } : false
+        };
+
+        // 연결 테스트 수행
+        const testResult = await DbConnectionManager.testConnection(
+          id,
+          existingConnection.db_type,
+          testConfig
+        );
+
+        if (!testResult.success) {
+          return {
+            success: false,
+            message: "새로운 연결 정보로 테스트에 실패했습니다. 수정할 수 없습니다.",
+            error: testResult.error ? `${testResult.error.code}: ${testResult.error.details}` : undefined
+          };
+        }
+      }
+
       // 업데이트 데이터 준비
       const updateData: any = {
         ...data,
         updated_date: new Date(),
       };
 
-      // 비밀번호가 변경된 경우 암호화
+      // 비밀번호가 변경된 경우 암호화 (연결 테스트 통과 후)
       if (data.password && data.password !== "***ENCRYPTED***") {
         updateData.password = PasswordEncryption.encrypt(data.password);
       } else {
@@ -320,7 +350,8 @@ export class ExternalDbConnectionService {
    * 데이터베이스 연결 테스트 (ID 기반)
    */
   static async testConnectionById(
-    id: number
+    id: number,
+    testData?: { password?: string }
   ): Promise<import("../types/externalDbTypes").ConnectionTestResult> {
     try {
       // 저장된 연결 정보 조회
@@ -339,9 +370,15 @@ export class ExternalDbConnectionService {
         };
       }
 
-      // 비밀번호 복호화
-      const decryptedPassword = await this.getDecryptedPassword(id);
-      if (!decryptedPassword) {
+      // 비밀번호 결정 (테스트용 비밀번호가 제공된 경우 그것을 사용, 아니면 저장된 비밀번호 복호화)
+      let password: string | null;
+      if (testData?.password) {
+        password = testData.password;
+      } else {
+        password = await this.getDecryptedPassword(id);
+      }
+
+      if (!password) {
         return {
           success: false,
           message: "비밀번호 복호화에 실패했습니다.",
@@ -358,7 +395,7 @@ export class ExternalDbConnectionService {
         port: connection.port,
         database: connection.database_name,
         user: connection.username,
-        password: decryptedPassword,
+        password: password,
         connectionTimeoutMillis: connection.connection_timeout != null ? connection.connection_timeout * 1000 : undefined,
         queryTimeoutMillis: connection.query_timeout != null ? connection.query_timeout * 1000 : undefined,
         ssl: connection.ssl_enabled === "Y" ? { rejectUnauthorized: false } : false
diff --git a/frontend/components/admin/ExternalDbConnectionModal.tsx b/frontend/components/admin/ExternalDbConnectionModal.tsx
index 4959f6fe..cb23768f 100644
--- a/frontend/components/admin/ExternalDbConnectionModal.tsx
+++ b/frontend/components/admin/ExternalDbConnectionModal.tsx
@@ -221,7 +221,7 @@ export const ExternalDbConnectionModal: React.FC<ExternalDbConnectionModalProps>
         return;
       }
 
-      const result = await ExternalDbConnectionAPI.testConnection(connection.id);
+      const result = await ExternalDbConnectionAPI.testConnection(connection.id, formData.password);
       setTestResult(result);
 
       if (result.success) {
diff --git a/frontend/lib/api/externalDbConnection.ts b/frontend/lib/api/externalDbConnection.ts
index ca6911db..d553a66f 100644
--- a/frontend/lib/api/externalDbConnection.ts
+++ b/frontend/lib/api/externalDbConnection.ts
@@ -205,10 +205,11 @@ export class ExternalDbConnectionAPI {
   /**
    * 데이터베이스 연결 테스트 (ID 기반)
    */
-  static async testConnection(connectionId: number): Promise<ConnectionTestResult> {
+  static async testConnection(connectionId: number, password?: string): Promise<ConnectionTestResult> {
     try {
       const response = await apiClient.post<ApiResponse<ConnectionTestResult>>(
-        `${this.BASE_PATH}/${connectionId}/test`
+        `${this.BASE_PATH}/${connectionId}/test`,
+        password ? { password } : undefined
       );
 
       if (!response.data.success) {