diff --git a/service/src/main/kotlin/com/sangdol/roomescape/reservation/business/ReservationService.kt b/service/src/main/kotlin/com/sangdol/roomescape/reservation/business/ReservationService.kt
index 6be365ad..8496801d 100644
--- a/service/src/main/kotlin/com/sangdol/roomescape/reservation/business/ReservationService.kt
+++ b/service/src/main/kotlin/com/sangdol/roomescape/reservation/business/ReservationService.kt
@@ -4,17 +4,14 @@ import com.sangdol.common.persistence.IDGenerator
 import com.sangdol.roomescape.common.types.CurrentUserContext
 import com.sangdol.roomescape.payment.business.PaymentService
 import com.sangdol.roomescape.payment.dto.PaymentResponse
-import com.sangdol.roomescape.reservation.dto.PendingReservationCreateRequest
-import com.sangdol.roomescape.reservation.dto.PendingReservationCreateResponse
-import com.sangdol.roomescape.reservation.dto.ReservationCancelRequest
-import com.sangdol.roomescape.reservation.dto.ReservationAdditionalResponse
-import com.sangdol.roomescape.reservation.dto.ReservationOverviewListResponse
-import com.sangdol.roomescape.reservation.mapper.toEntity
-import com.sangdol.roomescape.reservation.mapper.toOverviewResponse
-import com.sangdol.roomescape.reservation.mapper.toAdditionalResponse
+import com.sangdol.roomescape.reservation.dto.*
 import com.sangdol.roomescape.reservation.exception.ReservationErrorCode
 import com.sangdol.roomescape.reservation.exception.ReservationException
 import com.sangdol.roomescape.reservation.infrastructure.persistence.*
+import com.sangdol.roomescape.reservation.mapper.toAdditionalResponse
+import com.sangdol.roomescape.reservation.mapper.toEntity
+import com.sangdol.roomescape.reservation.mapper.toOverviewResponse
+import com.sangdol.roomescape.reservation.mapper.toStateResponse
 import com.sangdol.roomescape.schedule.business.ScheduleService
 import com.sangdol.roomescape.schedule.dto.ScheduleStateResponse
 import com.sangdol.roomescape.schedule.dto.ScheduleWithThemeAndStoreResponse
@@ -142,6 +139,30 @@ class ReservationService(
         }
     }
 
+    @Transactional(readOnly = true)
+    fun findStatusWithLock(id: Long): ReservationStateResponse {
+        log.info { "[findStatusWithLock] 예약 LOCK + 상태 조회 시작: reservationId=${id}" }
+
+        return reservationRepository.findByIdForUpdate(id)?.let {
+            log.info { "[findStatusWithLock] 예약 LOCK + 상태 조회 완료: reservationId=${id}" }
+            it.toStateResponse()
+        } ?: run {
+            log.warn { "[findStatusWithLock] 예약 LOCK + 상태 조회 실패: reservationId=${id}" }
+            throw ReservationException(ReservationErrorCode.RESERVATION_NOT_FOUND)
+        }
+    }
+
+    @Transactional
+    fun markInProgress(reservationId: Long) {
+        log.info { "[markInProgress] 예약 상태 ${ReservationStatus.PAYMENT_IN_PROGRESS} 변경 시작." }
+
+        findOrThrow(reservationId).apply {
+            this.status = ReservationStatus.PAYMENT_IN_PROGRESS
+        }.also {
+            log.info { "[markInProgress] 예약 상태 ${ReservationStatus.PAYMENT_IN_PROGRESS} 변경 완료" }
+        }
+    }
+
     private fun findOrThrow(id: Long): ReservationEntity {
         log.info { "[findOrThrow] 예약 조회 시작: reservationId=${id}" }
 
diff --git a/service/src/main/kotlin/com/sangdol/roomescape/reservation/dto/ReservationFindDTO.kt b/service/src/main/kotlin/com/sangdol/roomescape/reservation/dto/ReservationFindDTO.kt
index 7244a70f..29737d9c 100644
--- a/service/src/main/kotlin/com/sangdol/roomescape/reservation/dto/ReservationFindDTO.kt
+++ b/service/src/main/kotlin/com/sangdol/roomescape/reservation/dto/ReservationFindDTO.kt
@@ -35,3 +35,10 @@ data class ReserverInfo(
 data class ReservationOverviewListResponse(
     val reservations: List<ReservationOverviewResponse>
 )
+
+data class ReservationStateResponse(
+    val id: Long,
+    val scheduleId: Long,
+    val status: ReservationStatus,
+    val createdAt: Instant
+)
diff --git a/service/src/main/kotlin/com/sangdol/roomescape/reservation/infrastructure/persistence/ReservationRepository.kt b/service/src/main/kotlin/com/sangdol/roomescape/reservation/infrastructure/persistence/ReservationRepository.kt
index 7d1827f9..29a3500a 100644
--- a/service/src/main/kotlin/com/sangdol/roomescape/reservation/infrastructure/persistence/ReservationRepository.kt
+++ b/service/src/main/kotlin/com/sangdol/roomescape/reservation/infrastructure/persistence/ReservationRepository.kt
@@ -1,6 +1,8 @@
 package com.sangdol.roomescape.reservation.infrastructure.persistence
 
+import jakarta.persistence.LockModeType
 import org.springframework.data.jpa.repository.JpaRepository
+import org.springframework.data.jpa.repository.Lock
 import org.springframework.data.jpa.repository.Modifying
 import org.springframework.data.jpa.repository.Query
 import org.springframework.data.repository.query.Param
@@ -10,6 +12,10 @@ interface ReservationRepository : JpaRepository<ReservationEntity, Long> {
 
     fun findAllByUserIdAndStatusIsIn(userId: Long, statuses: List<ReservationStatus>): List<ReservationEntity>
 
+    @Lock(LockModeType.PESSIMISTIC_WRITE)
+    @Query("SELECT r FROM ReservationEntity r WHERE r._id = :id")
+    fun findByIdForUpdate(@Param("id") id: Long): ReservationEntity?
+
     @Modifying
     @Query(
         """
diff --git a/service/src/main/kotlin/com/sangdol/roomescape/reservation/mapper/ReservationMappingExtensions.kt b/service/src/main/kotlin/com/sangdol/roomescape/reservation/mapper/ReservationMappingExtensions.kt
index 052fffd4..33762eeb 100644
--- a/service/src/main/kotlin/com/sangdol/roomescape/reservation/mapper/ReservationMappingExtensions.kt
+++ b/service/src/main/kotlin/com/sangdol/roomescape/reservation/mapper/ReservationMappingExtensions.kt
@@ -4,6 +4,7 @@ import com.sangdol.roomescape.payment.dto.PaymentResponse
 import com.sangdol.roomescape.reservation.dto.PendingReservationCreateRequest
 import com.sangdol.roomescape.reservation.dto.ReservationAdditionalResponse
 import com.sangdol.roomescape.reservation.dto.ReservationOverviewResponse
+import com.sangdol.roomescape.reservation.dto.ReservationStateResponse
 import com.sangdol.roomescape.reservation.dto.ReserverInfo
 import com.sangdol.roomescape.reservation.infrastructure.persistence.ReservationEntity
 import com.sangdol.roomescape.reservation.infrastructure.persistence.ReservationStatus
@@ -57,3 +58,10 @@ private fun ReservationEntity.toReserverInfo() = ReserverInfo(
     participantCount = this.participantCount,
     requirement = this.requirement
 )
+
+fun ReservationEntity.toStateResponse() = ReservationStateResponse(
+    id = this.id,
+    scheduleId = this.scheduleId,
+    status = this.status,
+    createdAt = this.createdAt
+)