diff --git a/user-management/migrations/20260326_add_product_types.sql b/user-management/migrations/20260326_add_product_types.sql
index f3f9f8b..b7b2541 100644
--- a/user-management/migrations/20260326_add_product_types.sql
+++ b/user-management/migrations/20260326_add_product_types.sql
@@ -15,8 +15,5 @@ INSERT IGNORE INTO product_types (code, name, display_order) VALUES
   ('HX', '열교환기', 3),
   ('SKID', 'Skid', 4);
 
--- projects에 product_type_id FK 추가
-ALTER TABLE projects ADD COLUMN product_type_id INT NULL;
-
-ALTER TABLE projects ADD CONSTRAINT fk_project_product_type
-  FOREIGN KEY (product_type_id) REFERENCES product_types(id)
+-- projects에 product_type_id FK 추가 (멱등성: 이미 존재하면 무시)
+ALTER TABLE projects ADD COLUMN IF NOT EXISTS product_type_id INT NULL