diff --git a/application/src/main/kotlin/tw/waterballsa/gaas/application/repositories/RoomRepository.kt b/application/src/main/kotlin/tw/waterballsa/gaas/application/repositories/RoomRepository.kt
index abf1c15a..e3abd6f4 100644
--- a/application/src/main/kotlin/tw/waterballsa/gaas/application/repositories/RoomRepository.kt
+++ b/application/src/main/kotlin/tw/waterballsa/gaas/application/repositories/RoomRepository.kt
@@ -12,4 +12,5 @@ interface RoomRepository {
     fun update(room: Room): Room
     fun findByStatus(status: Room.Status, page: Pagination<Any>): Pagination<Room>
     fun deleteById(roomId: Room.Id)
+    fun leaveRoom(room: Room)
 }
diff --git a/application/src/main/kotlin/tw/waterballsa/gaas/application/usecases/LeaveRoomUsecase.kt b/application/src/main/kotlin/tw/waterballsa/gaas/application/usecases/LeaveRoomUsecase.kt
new file mode 100644
index 00000000..83ecbde3
--- /dev/null
+++ b/application/src/main/kotlin/tw/waterballsa/gaas/application/usecases/LeaveRoomUsecase.kt
@@ -0,0 +1,33 @@
+package tw.waterballsa.gaas.application.usecases
+
+import tw.waterballsa.gaas.application.eventbus.EventBus
+import tw.waterballsa.gaas.application.repositories.RoomRepository
+import tw.waterballsa.gaas.domain.Room
+import tw.waterballsa.gaas.domain.Room.Player
+import tw.waterballsa.gaas.exceptions.NotFoundException.Companion.notFound
+import javax.inject.Named
+
+@Named
+class LeaveRoomUsecase(
+    private val roomRepository: RoomRepository,
+    private val eventBus: EventBus
+) {
+
+    fun execute(request: LeaveRoomUsecase.Request) {
+        with(request) {
+            val room = findRoomById(Room.Id(roomId))
+            room.leaveRoom(Player.Id(playerId))
+            roomRepository.leaveRoom(room)
+        }
+    }
+
+    private fun findRoomById(roomId: Room.Id) =
+        roomRepository.findById(roomId)
+            ?: throw notFound(Room::class).id(roomId)
+
+    data class Request(
+        val roomId: String,
+        val playerId: String
+    )
+
+}
\ No newline at end of file
diff --git a/domain/src/main/kotlin/tw/waterballsa/gaas/domain/Room.kt b/domain/src/main/kotlin/tw/waterballsa/gaas/domain/Room.kt
index dbfb9a8e..6f092d0c 100644
--- a/domain/src/main/kotlin/tw/waterballsa/gaas/domain/Room.kt
+++ b/domain/src/main/kotlin/tw/waterballsa/gaas/domain/Room.kt
@@ -6,7 +6,7 @@ import tw.waterballsa.gaas.exceptions.PlatformException
 class Room(
     var roomId: Id? = null,
     val game: GameRegistration,
-    val host: Player,
+    var host: Player,
     val players: MutableList<Player>,
     val maxPlayers: Int,
     val minPlayers: Int,
@@ -44,6 +44,18 @@ class Room(
         players.remove(player)
     }
 
+    fun leaveRoom(playerId: Player.Id) {
+        players.removeIf { it.id == playerId }
+        if (playerId == host.id) {
+            changeHost()
+        }
+    }
+
+    private fun changeHost() {
+        players.firstOrNull()
+            ?.let { host = it }
+    }
+
     private fun findPlayer(playerId: Player.Id): Player? = players.find { it.id == playerId }
 
     @JvmInline
diff --git a/spring/src/main/kotlin/tw/waterballsa/gaas/spring/controllers/RoomController.kt b/spring/src/main/kotlin/tw/waterballsa/gaas/spring/controllers/RoomController.kt
index aa72daec..bcd98893 100644
--- a/spring/src/main/kotlin/tw/waterballsa/gaas/spring/controllers/RoomController.kt
+++ b/spring/src/main/kotlin/tw/waterballsa/gaas/spring/controllers/RoomController.kt
@@ -29,7 +29,8 @@ class RoomController(
     private val getRoomsUseCase: GetRoomsUseCase,
     private val closeRoomsUseCase: CloseRoomUsecase,
     private val changePlayerReadinessUsecase: ChangePlayerReadinessUsecase,
-    private val kickPlayerUseCase: KickPlayerUsecase
+    private val kickPlayerUseCase: KickPlayerUsecase,
+    private val leaveRoomUsecase: LeaveRoomUsecase
 ) {
     @PostMapping
     fun createRoom(
@@ -112,6 +113,16 @@ class RoomController(
         return PlatformViewModel.success()
     }
 
+    @DeleteMapping("/{roomId}/players/me")
+    @ResponseStatus(NO_CONTENT)
+    fun leaveRoom(
+        @AuthenticationPrincipal jwt: Jwt,
+        @PathVariable roomId: String
+    ) {
+        val leaverId = jwt.subject ?: throw PlatformException("User id must exist.")
+        leaveRoomUsecase.execute(LeaveRoomUsecase.Request(roomId, leaverId))
+    }
+
     class CreateRoomRequest(
         private val name: String,
         private val gameId: String,
diff --git a/spring/src/main/kotlin/tw/waterballsa/gaas/spring/repositories/SpringRoomRepositoryImpl.kt b/spring/src/main/kotlin/tw/waterballsa/gaas/spring/repositories/SpringRoomRepositoryImpl.kt
index 67b5ef8b..22871c63 100644
--- a/spring/src/main/kotlin/tw/waterballsa/gaas/spring/repositories/SpringRoomRepositoryImpl.kt
+++ b/spring/src/main/kotlin/tw/waterballsa/gaas/spring/repositories/SpringRoomRepositoryImpl.kt
@@ -42,6 +42,10 @@ class SpringRoomRepository(
         roomDAO.deleteById(roomId.value)
     }
 
+    override fun leaveRoom(room: Room) {
+        roomDAO.save(room.toData())
+    }
+
     private fun RoomData.toDomain(): Room =
         Room(
             roomId = Id(id!!),
diff --git a/spring/src/test/kotlin/tw/waterballsa/gaas/spring/it/controllers/RoomControllerTest.kt b/spring/src/test/kotlin/tw/waterballsa/gaas/spring/it/controllers/RoomControllerTest.kt
index f4996f00..50cf8d45 100644
--- a/spring/src/test/kotlin/tw/waterballsa/gaas/spring/it/controllers/RoomControllerTest.kt
+++ b/spring/src/test/kotlin/tw/waterballsa/gaas/spring/it/controllers/RoomControllerTest.kt
@@ -1,18 +1,18 @@
 package tw.waterballsa.gaas.spring.it.controllers
 
-import org.assertj.core.api.Assertions.*
+import org.assertj.core.api.Assertions.assertThat
 import org.junit.jupiter.api.AfterEach
+import org.junit.jupiter.api.Assertions.assertFalse
 import org.junit.jupiter.api.BeforeEach
 import org.junit.jupiter.api.Test
 import org.springframework.beans.factory.annotation.Autowired
 import org.springframework.security.oauth2.core.oidc.OidcIdToken
 import org.springframework.security.oauth2.core.oidc.user.DefaultOidcUser
 import org.springframework.security.oauth2.core.oidc.user.OidcUser
+import org.springframework.security.oauth2.jwt.Jwt
 import org.springframework.security.test.web.servlet.request.SecurityMockMvcRequestPostProcessors.oidcLogin
 import org.springframework.test.web.servlet.ResultActions
-import org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get
-import org.springframework.test.web.servlet.request.MockMvcRequestBuilders.post
-import org.springframework.test.web.servlet.request.MockMvcRequestBuilders.delete
+import org.springframework.test.web.servlet.request.MockMvcRequestBuilders.*
 import org.springframework.test.web.servlet.result.MockMvcResultMatchers.jsonPath
 import org.springframework.test.web.servlet.result.MockMvcResultMatchers.status
 import tw.waterballsa.gaas.application.model.Pagination
@@ -272,6 +272,18 @@ class RoomControllerTest @Autowired constructor(
             .thenPlayersShouldBeInTheRoom(roomC.roomId!!, hostA, playerB)
     }
 
+    @Test
+    fun givenHostAndPlayerBAndPlayerCAreInRoomD_WhenHostLeaveRoomD_ThenPreviousHostShouldBeNotInRoomDAndChangedNewHost() {
+        val userA = testUser
+        val host = userA.toRoomPlayer()
+        val playerB = createUser("2", "test2@mail.com", "winner1122").toRoomPlayer()
+        val playerC = createUser("3", "test3@mail.com", "winner0033").toRoomPlayer()
+
+        givenHostAndPlayersAreInTheRoom(host, playerB, playerC)
+            .whenUserLeaveTheRoom(userA)
+            .thenPlayerShouldBeNotInRoomAndHostIsChanged(host)
+    }
+
     private fun TestGetRoomsRequest.whenUserAVisitLobby(joinUser: User): ResultActions =
         mockMvc.perform(
             get("/rooms")
@@ -325,6 +337,12 @@ class RoomControllerTest @Autowired constructor(
                 .withJwt(user.id!!.value.toJwt())
         )
 
+    private fun leaveRoom(leaveUser: Jwt): ResultActions =
+        mockMvc.perform(
+            delete("/rooms/${testRoom.roomId!!.value}/players/me")
+                .withJwt(leaveUser)
+        )
+
     private fun givenTheHostCreatePublicRoom(host: User): Room {
         testRoom = createRoom(host)
         return testRoom
@@ -335,6 +353,12 @@ class RoomControllerTest @Autowired constructor(
         return testRoom
     }
 
+    private fun givenHostAndPlayersAreInTheRoom(host: Player, vararg players: Player): Room {
+        val combinedPlayers = (listOf(host) + players).toMutableList()
+        testRoom = createRoom(host, combinedPlayers)
+        return testRoom
+    }
+
     private fun Room.whenUserJoinTheRoom(user: User, password: String? = null): ResultActions {
         val request = joinRoomRequest(password)
         val joinUser = mockOidcUser(user)
@@ -349,6 +373,11 @@ class RoomControllerTest @Autowired constructor(
         post("/rooms/${roomId.value}/players/me:cancel").withJwt(user.id!!.value.toJwt())
     )
 
+    private fun Room.whenUserLeaveTheRoom(user: User): ResultActions {
+        val leaveUser = user.id!!.value.toJwt()
+        return leaveRoom(leaveUser)
+    }
+
     private fun ResultActions.thenCreateRoomSuccessfully(request: TestCreateRoomRequest) {
         request.let {
             andExpect(status().isCreated)
@@ -380,6 +409,13 @@ class RoomControllerTest @Autowired constructor(
             .andExpect(jsonPath("$.message").value("${resourceType.simpleName} not found"))
     }
 
+    private fun ResultActions.thenPlayerShouldBeNotInRoomAndHostIsChanged(player: Player) {
+        andExpect(status().isNoContent)
+        val room = roomRepository.findById(testRoom.roomId!!)!!
+        assertFalse(room.hasPlayer(player.id))
+        assertFalse(room.isHost(player.id))
+    }
+
     private fun createUser(id: String, email: String, nickname: String): User =
         userRepository.createUser(User(User.Id(id), email, nickname))
 
@@ -411,6 +447,20 @@ class RoomControllerTest @Autowired constructor(
             )
         )
 
+    private fun createRoom(host: Player, players: MutableList<Player>, password: String? = null): Room =
+        roomRepository.createRoom(
+            Room(
+                game = testGame,
+                host = host,
+                players = players,
+                maxPlayers = testGame.maxPlayers,
+                minPlayers = testGame.minPlayers,
+                name = "My Room",
+                status = Room.Status.WAITING,
+                password = password
+            )
+        )
+
     private fun createRoomRequest(password: String? = null): TestCreateRoomRequest =
         TestCreateRoomRequest(
             name = "Rapid Mahjong Room",
@@ -466,4 +516,13 @@ class RoomControllerTest @Autowired constructor(
         findRoomById(roomId)!!.players.map { it.id.value }.let {
             assertThat(it).containsAll(users.map { user -> user.id!!.value })
         }
+
+    private fun User.toRoomPlayer(): Player =
+        Player(Player.Id(id!!.value), nickname)
+
+    private fun Room.hasPlayer(playerId: Player.Id): Boolean =
+        players.any { it.id == playerId }
+
+    private fun Room.isHost(playerId: Player.Id): Boolean =
+        host.id == playerId
 }