diff --git a/user-management/migrations/20260323_sprint001_vacation_overhaul.sql b/user-management/migrations/20260323_sprint001_vacation_overhaul.sql
index eeddb82..90b28b5 100644
--- a/user-management/migrations/20260323_sprint001_vacation_overhaul.sql
+++ b/user-management/migrations/20260323_sprint001_vacation_overhaul.sql
@@ -61,13 +61,13 @@ ALTER TABLE sp_vacation_balances
   ADD COLUMN IF NOT EXISTS expires_at DATE NULL COMMENT '만료일 (NULL=해당연도말)';
 
 -- UNIQUE KEY 변경: balance_type을 포함하여 같은 user/type/year에 AUTO + LONG_SERVICE 공존 허용
--- 기존 UNIQUE KEY 삭제 후 재생성
-ALTER TABLE sp_vacation_balances
-  DROP INDEX IF EXISTS unique_user_type_year;
-
+-- 새 인덱스를 먼저 추가해야 FK(user_id)가 새 인덱스를 참조 가능
 ALTER TABLE sp_vacation_balances
   ADD UNIQUE KEY unique_user_type_year_btype (user_id, vacation_type_id, year, balance_type);
 
+ALTER TABLE sp_vacation_balances
+  DROP INDEX IF EXISTS unique_user_type_year;
+
 -- ============================================================
 -- 5. sso_users에 장기근속 제외 플래그
 -- ============================================================