diff --git a/service/src/main/kotlin/com/sangdol/roomescape/order/business/OrderService.kt b/service/src/main/kotlin/com/sangdol/roomescape/order/business/OrderService.kt
index 1662d322..76a9dcdc 100644
--- a/service/src/main/kotlin/com/sangdol/roomescape/order/business/OrderService.kt
+++ b/service/src/main/kotlin/com/sangdol/roomescape/order/business/OrderService.kt
@@ -36,14 +36,18 @@ class OrderService(
 ) {
 
     fun confirm(reservationId: Long, paymentConfirmRequest: PaymentConfirmRequest) {
-        val trial = paymentAttemptRepository.countByReservationId(reservationId)
+        var trial: Long = 0
         val paymentKey = paymentConfirmRequest.paymentKey
 
         log.info { "[confirm] 결제 및 예약 확정 시작: reservationId=${reservationId}, paymentKey=${paymentKey}" }
-
         try {
-            transactionExecutionUtil.withNewTransaction(isReadOnly = false) {
-                validateAndMarkInProgress(reservationId)
+            trial = transactionExecutionUtil.withNewTransaction(isReadOnly = false) {
+                getTrialAfterValidateCanConfirm(reservationId).also {
+                    reservationService.markInProgress(reservationId)
+                }
+            } ?: run {
+                log.warn { "[confirm] 모든 paymentAttempts 조회 과정에서의 예상치 못한 null 응답: reservationId=${reservationId}" }
+                throw OrderException(OrderErrorCode.BOOKING_UNEXPECTED_ERROR)
             }
 
             val paymentClientResponse: PaymentGatewayResponse =
@@ -61,20 +65,32 @@ class OrderService(
         }
     }
 
-    private fun validateAndMarkInProgress(reservationId: Long) {
+    private fun getTrialAfterValidateCanConfirm(reservationId: Long): Long {
         log.info { "[validateAndMarkInProgress] 예약 확정 가능 여부 검증 시작: reservationId=${reservationId}" }
         val reservation: ReservationStateResponse = reservationService.findStatusWithLock(reservationId)
         val schedule: ScheduleStateResponse = scheduleService.findStateWithLock(reservation.scheduleId)
 
         try {
             orderValidator.validateCanConfirm(reservation, schedule)
-            log.info { "[validateAndMarkInProgress] 예약 확정 가능 여부 검증 완료: reservationId=${reservationId}" }
+
+            return getTrialIfSuccessAttemptNotExists(reservationId).also {
+                log.info { "[validateAndMarkInProgress] 예약 확정 가능 여부 검증 완료: reservationId=${reservationId}" }
+            }
         } catch (e: OrderException) {
             val errorCode = OrderErrorCode.NOT_CONFIRMABLE
             throw OrderException(errorCode, e.message)
         }
+    }
 
-        reservationService.markInProgress(reservationId)
+    private fun getTrialIfSuccessAttemptNotExists(reservationId: Long): Long {
+        val paymentAttempts: List<PaymentAttemptEntity> = paymentAttemptRepository.findAllByReservationId(reservationId)
+
+        if (paymentAttempts.any { it.result == AttemptResult.SUCCESS }) {
+            log.info { "[validateCanConfirm] 이미 결제 완료된 예약: id=${reservationId}" }
+            throw OrderException(OrderErrorCode.BOOKING_ALREADY_COMPLETED)
+        }
+
+        return paymentAttempts.size.toLong()
     }
 
     private fun requestConfirmPayment(
diff --git a/service/src/main/kotlin/com/sangdol/roomescape/order/business/OrderValidator.kt b/service/src/main/kotlin/com/sangdol/roomescape/order/business/OrderValidator.kt
index 8ee18671..7be57c88 100644
--- a/service/src/main/kotlin/com/sangdol/roomescape/order/business/OrderValidator.kt
+++ b/service/src/main/kotlin/com/sangdol/roomescape/order/business/OrderValidator.kt
@@ -16,18 +16,11 @@ import java.time.LocalDateTime
 private val log: KLogger = KotlinLogging.logger {}
 
 @Component
-class OrderValidator(
-    private val paymentAttemptRepository: PaymentAttemptRepository
-) {
+class OrderValidator {
     fun validateCanConfirm(
         reservation: ReservationStateResponse,
         schedule: ScheduleStateResponse
     ) {
-        if (paymentAttemptRepository.isSuccessAttemptExists(reservation.id)) {
-            log.info { "[validateCanConfirm] 이미 결제 완료된 예약: id=${reservation.id}" }
-            throw OrderException(OrderErrorCode.BOOKING_ALREADY_COMPLETED)
-        }
-
         validateReservationStatus(reservation)
         validateScheduleStatus(schedule)
     }
diff --git a/service/src/main/kotlin/com/sangdol/roomescape/order/infrastructure/persistence/PaymentAttemptRepository.kt b/service/src/main/kotlin/com/sangdol/roomescape/order/infrastructure/persistence/PaymentAttemptRepository.kt
index 3c5e8666..4f2ff58f 100644
--- a/service/src/main/kotlin/com/sangdol/roomescape/order/infrastructure/persistence/PaymentAttemptRepository.kt
+++ b/service/src/main/kotlin/com/sangdol/roomescape/order/infrastructure/persistence/PaymentAttemptRepository.kt
@@ -23,4 +23,6 @@ interface PaymentAttemptRepository: JpaRepository<PaymentAttemptEntity, Long> {
     """
     )
     fun isSuccessAttemptExists(reservationId: Long): Boolean
+
+    fun findAllByReservationId(reservationId: Long): List<PaymentAttemptEntity>
 }