diff --git a/src/application/payment/payment.service.ts b/src/application/payment/payment.service.ts
index 1ef0b00..38e8725 100644
--- a/src/application/payment/payment.service.ts
+++ b/src/application/payment/payment.service.ts
@@ -75,7 +75,7 @@ export class PaymentService {
     }
     const verifyData = await this.paymentGateway.verifyPayment({ authority, amount: paymentData.amount });
     if (verifyData.code === 100 || verifyData.code === 101) {
-      const purchase = await this.purchaseDataAccess.createPurchase(paymentData.userId.toString(), paymentData.courseId.toString(), paymentData._id);
+      const purchase = await this.purchaseDataAccess.createPurchase(paymentData.userId.toString(), paymentData.courseId.toString(), paymentData._id.toString());
       console.log(purchase)
       const registerCourse = await this.userDataAccess.registerCourse(paymentData.userId, paymentData.courseId);
       console.log(registerCourse)