diff --git a/src/main/kotlin/club/sakunadaisuki/pcrediveclanrecordbackend/database/service/MemberService.kt b/src/main/kotlin/club/sakunadaisuki/pcrediveclanrecordbackend/database/service/MemberService.kt
index d66d454..1beae6a 100644
--- a/src/main/kotlin/club/sakunadaisuki/pcrediveclanrecordbackend/database/service/MemberService.kt
+++ b/src/main/kotlin/club/sakunadaisuki/pcrediveclanrecordbackend/database/service/MemberService.kt
@@ -17,13 +17,13 @@ class MemberService(private val database: MongoDatabase) {
     }
 
     // Create new member
-    suspend fun create(data: MemberDto): String = withContext(Dispatchers.IO) {
+    suspend fun create(data: MemberDto): MemberDto = withContext(Dispatchers.IO) {
         data.createAt = System.currentTimeMillis()
         data.updatedAt = System.currentTimeMillis()
         data.leave = false
         val doc = data.toDocument()
         collection.insertOne(doc)
-        doc["uid"].toString()
+        doc.let(MemberDto::fromDocument)
     }
 
     // Read a member
@@ -37,8 +37,9 @@ class MemberService(private val database: MongoDatabase) {
     }
 
     // Update a member
-    suspend fun update(uid: String, data: MemberDto): Document? = withContext(Dispatchers.IO) {
+    suspend fun update(uid: String, data: MemberDto): MemberDto? = withContext(Dispatchers.IO) {
         collection.findOneAndReplace(Filters.eq("uid", uid), data.toDocument())
+        collection.find(Filters.eq("uid", uid)).first()?.let(MemberDto::fromDocument)
     }
 
     // Delete a member
diff --git a/src/main/kotlin/club/sakunadaisuki/pcrediveclanrecordbackend/plugins/Mongo.kt b/src/main/kotlin/club/sakunadaisuki/pcrediveclanrecordbackend/plugins/Mongo.kt
index 4906f90..a0668b7 100644
--- a/src/main/kotlin/club/sakunadaisuki/pcrediveclanrecordbackend/plugins/Mongo.kt
+++ b/src/main/kotlin/club/sakunadaisuki/pcrediveclanrecordbackend/plugins/Mongo.kt
@@ -44,8 +44,13 @@ fun Application.configureMongo() {
             // Create member
             post("/member") {
                 val member = call.receive<MemberRequest>()
-                val id = memberService.create(member.toDto())
-                call.respond(HttpStatusCode.Created, id)
+                val existMember = memberService.read(member.uid)
+                if (existMember == null) {
+                    val id = memberService.create(member.toDto())
+                    call.respond(HttpStatusCode.Created, id)
+                } else {
+                    call.respond(HttpStatusCode.Conflict)
+                }
             }
             // Update member
             put("/member/{uid}") {