diff --git a/backend/src/migrations/1783000000000-AddDriveFileExtractDropProjectAttachments.ts b/backend/src/migrations/1783000000000-AddDriveFileExtractDropProjectAttachments.ts
index 6853e7b..7e54240 100644
--- a/backend/src/migrations/1783000000000-AddDriveFileExtractDropProjectAttachments.ts
+++ b/backend/src/migrations/1783000000000-AddDriveFileExtractDropProjectAttachments.ts
@@ -5,35 +5,35 @@ import { MigrationInterface, QueryRunner } from 'typeorm';
 //   → 연동 폴더 문서를 NCP 에서 받아 텍스트 추출·캐싱(AI 업무 추천 주입)
 // - 프로젝트 직접 업로드(project_attachments) 폐기 → 테이블 제거(완전 대체)
 // 운영(migrationsRun)에서만 실행되며, dev 는 synchronize 로 자동 반영된다.
+//
+// 멱등·견고하게 작성: 과거 synchronize 로 만들어진 운영 DB(제약 이름 상이)나
+// 부분 적용 상태에서도 실패하지 않도록 IF [NOT] EXISTS / CASCADE 를 사용한다.
 export class AddDriveFileExtractDropProjectAttachments1783000000000 implements MigrationInterface {
   name = 'AddDriveFileExtractDropProjectAttachments1783000000000';
 
   public async up(queryRunner: QueryRunner): Promise<void> {
-    // 1) drive_files AI 추출 캐시 컬럼
+    // 1) drive_files AI 추출 캐시 컬럼 (이미 있으면 건너뜀)
     await queryRunner.query(
-      `ALTER TABLE "drive_files" ADD "extracted_text" text`,
+      `ALTER TABLE "drive_files" ADD COLUMN IF NOT EXISTS "extracted_text" text`,
     );
     await queryRunner.query(
-      `ALTER TABLE "drive_files" ADD "extract_status" character varying NOT NULL DEFAULT 'pending'`,
+      `ALTER TABLE "drive_files" ADD COLUMN IF NOT EXISTS "extract_status" character varying NOT NULL DEFAULT 'pending'`,
     );
 
     // 2) project_attachments 폐기 (드라이브 연동으로 대체)
+    //    제약 이름에 의존하지 않도록 CASCADE 로 테이블·FK 를 한 번에 제거.
     await queryRunner.query(
-      `ALTER TABLE "project_attachments" DROP CONSTRAINT "FK_project_attachments_uploader"`,
+      `DROP TABLE IF EXISTS "project_attachments" CASCADE`,
     );
-    await queryRunner.query(
-      `ALTER TABLE "project_attachments" DROP CONSTRAINT "FK_project_attachments_project"`,
-    );
-    await queryRunner.query(`DROP TABLE "project_attachments"`);
   }
 
   public async down(queryRunner: QueryRunner): Promise<void> {
     // 1) project_attachments 복원 (AddProjectAttachments + ExtractedText 와 동일 스키마)
     await queryRunner.query(
-      `CREATE TABLE "project_attachments" ("id" uuid NOT NULL DEFAULT uuid_generate_v4(), "name" character varying NOT NULL, "stored_name" character varying NOT NULL, "size" integer NOT NULL, "mime" character varying NOT NULL, "kind" character varying NOT NULL, "extracted_text" text, "created_at" TIMESTAMP NOT NULL DEFAULT now(), "project_id" uuid, "uploader_id" uuid, CONSTRAINT "PK_project_attachments" PRIMARY KEY ("id"))`,
+      `CREATE TABLE IF NOT EXISTS "project_attachments" ("id" uuid NOT NULL DEFAULT uuid_generate_v4(), "name" character varying NOT NULL, "stored_name" character varying NOT NULL, "size" integer NOT NULL, "mime" character varying NOT NULL, "kind" character varying NOT NULL, "extracted_text" text, "created_at" TIMESTAMP NOT NULL DEFAULT now(), "project_id" uuid, "uploader_id" uuid, CONSTRAINT "PK_project_attachments" PRIMARY KEY ("id"))`,
     );
     await queryRunner.query(
-      `CREATE INDEX "IDX_project_attachments_project" ON "project_attachments" ("project_id")`,
+      `CREATE INDEX IF NOT EXISTS "IDX_project_attachments_project" ON "project_attachments" ("project_id")`,
     );
     await queryRunner.query(
       `ALTER TABLE "project_attachments" ADD CONSTRAINT "FK_project_attachments_project" FOREIGN KEY ("project_id") REFERENCES "projects"("id") ON DELETE CASCADE ON UPDATE NO ACTION`,
@@ -44,10 +44,10 @@ export class AddDriveFileExtractDropProjectAttachments1783000000000 implements M
 
     // 2) drive_files 추출 캐시 컬럼 제거
     await queryRunner.query(
-      `ALTER TABLE "drive_files" DROP COLUMN "extract_status"`,
+      `ALTER TABLE "drive_files" DROP COLUMN IF EXISTS "extract_status"`,
     );
     await queryRunner.query(
-      `ALTER TABLE "drive_files" DROP COLUMN "extracted_text"`,
+      `ALTER TABLE "drive_files" DROP COLUMN IF EXISTS "extracted_text"`,
     );
   }
 }