diff --git a/src/main/kotlin/com/hero/alignlab/config/web/ReactiveConcurrentUserWebSocketHandler.kt b/src/main/kotlin/com/hero/alignlab/config/web/ReactiveConcurrentUserWebSocketHandler.kt
index f855bf5..9fa9ef3 100644
--- a/src/main/kotlin/com/hero/alignlab/config/web/ReactiveConcurrentUserWebSocketHandler.kt
+++ b/src/main/kotlin/com/hero/alignlab/config/web/ReactiveConcurrentUserWebSocketHandler.kt
@@ -19,6 +19,7 @@ import reactor.core.publisher.Mono
 import java.time.Duration
 import java.time.LocalDateTime
 
+// rsocket의 경우, client의 requester 처리에 있어 부가적인 설정이 필요. 그러므로 reactive websocket으로 진행
 // poc 용도의 handler, 리펙토링 예정
 @Component
 class ReactiveConcurrentUserWebSocketHandler(
@@ -104,7 +105,11 @@ class ReactiveConcurrentUserWebSocketHandler(
             Flux.interval(Duration.ofMillis(1000L))
                 .zipWith(eventFlux) { _, event -> event }
                 .map(session::textMessage)
-        ).and(session.receive().map(WebSocketMessage::getPayloadAsText).log()).then()
+        ).and(session.receive().map(WebSocketMessage::getPayloadAsText).log())
+            .doFinally {
+                handleSessionTermination(session, user.uid)
+            }
+            .then()
     }
 
     private fun isTokenHeader(headerKey: String): Boolean {
@@ -116,6 +121,66 @@ class ReactiveConcurrentUserWebSocketHandler(
         val regex = Regex("/ws/v1/groups/(\\w+)/concurrent-users")
         return regex.find(uri)?.groupValues?.get(1)
     }
+
+    private fun removeSessionFromMap(session: WebSocketSession) {
+        concurrentUserMap.forEach { (groupId, uidBySession) ->
+            val userToRemove = uidBySession.filterValues { it == session }.keys.firstOrNull()
+            if (userToRemove != null) {
+                uidBySession.remove(userToRemove)
+                logger.info { "Removed session for user $userToRemove from group $groupId" }
+                if (uidBySession.isEmpty()) {
+                    concurrentUserMap.remove(groupId)
+                    logger.info { "Removed group $groupId as it has no more users." }
+                }
+            }
+        }
+    }
+
+    private fun handleSessionTermination(session: WebSocketSession, uid: Long) {
+        concurrentUserMap.forEach { (groupId, uidBySession) ->
+            val removedUser = uidBySession.remove(uid)
+
+            if (removedUser != null) {
+                logger.info { "Removed session for user $uid from group $groupId" }
+
+                if (uidBySession.isEmpty()) {
+                    concurrentUserMap.remove(groupId)
+                    logger.info { "Removed group $groupId as it has no more users." }
+                } else {
+                    // Send the updated group status to remaining users
+                    sendUpdatedGroupStatus(groupId, uidBySession)
+                }
+            }
+        }
+    }
+
+    private fun sendUpdatedGroupStatus(groupId: Long, uidBySession: MutableMap<Long, WebSocketSession>) {
+        val uids = uidBySession.keys
+        val userInfoByUid = userInfoService.findAllByIds(uids.toList()).associateBy { it.id }
+
+        val groupUsers = groupUserService.findAllByGroupIdAndUids(groupId, userInfoByUid.keys)
+            .associateBy { it.uid }
+
+        val message = ConcurrentMessage(
+            groupId = groupId,
+            groupUsers = userInfoByUid.mapNotNull { (uid, info) ->
+                val groupUser = groupUsers[uid] ?: return@mapNotNull null
+
+                ConcurrentMessage.ConcurrentUser(
+                    groupUserId = groupUser.id,
+                    uid = uid,
+                    nickname = info.nickname
+                )
+            }
+        )
+
+        uidBySession.forEach { (_, websocketSession) ->
+            websocketSession
+                .send(Mono.just(websocketSession.textMessage(mapper.writeValueAsString(message))))
+                .subscribe()
+        }
+    }
+
 }
 
 data class ConcurrentMessage(