diff --git a/backend-node/src/controllers/adminController.ts b/backend-node/src/controllers/adminController.ts
index cc6b751e..e2e03e92 100644
--- a/backend-node/src/controllers/adminController.ts
+++ b/backend-node/src/controllers/adminController.ts
@@ -1523,7 +1523,7 @@ export const getUserInfo = async (req: AuthenticatedRequest, res: Response) => {
       partnerObjid: user.partner_objid,
       rank: user.rank,
       photo: user.photo
-        ? `data:image/jpeg;base64,${user.photo.toString("base64")}`
+        ? `data:image/jpeg;base64,${Buffer.from(user.photo).toString("base64")}`
         : null,
       locale: user.locale,
       companyCode: user.company_code,
@@ -2415,7 +2415,7 @@ export const updateProfile = async (
     const responseData = {
       ...updatedUser,
       photo: updatedUser?.photo
-        ? `data:image/jpeg;base64,${updatedUser.photo.toString("base64")}`
+        ? `data:image/jpeg;base64,${Buffer.from(updatedUser.photo).toString("base64")}`
         : null,
     };
 
diff --git a/backend-node/src/services/authService.ts b/backend-node/src/services/authService.ts
index e02cd5b5..1502b97f 100644
--- a/backend-node/src/services/authService.ts
+++ b/backend-node/src/services/authService.ts
@@ -217,7 +217,7 @@ export class AuthService {
         authName: authNames || undefined,
         companyCode: userInfo.company_code || "ILSHIN",
         photo: userInfo.photo
-          ? `data:image/jpeg;base64,${userInfo.photo.toString("base64")}`
+          ? `data:image/jpeg;base64,${Buffer.from(userInfo.photo).toString("base64")}`
           : undefined,
         locale: userInfo.locale || "KR",
       };