diff --git a/Server/SQL/DynamicData.cs b/Server/SQL/DynamicData.cs
index 24dbb00..80d480c 100644
--- a/Server/SQL/DynamicData.cs
+++ b/Server/SQL/DynamicData.cs
@@ -1,4 +1,5 @@
 using Microsoft.EntityFrameworkCore;
+using System.ComponentModel.DataAnnotations;
 using System.ComponentModel.DataAnnotations.Schema;
 
 namespace Server.SQL
@@ -6,6 +7,7 @@ namespace Server.SQL
     [Table("dynamic_data", Schema = "gamedb")]
     public class DynamicData
     {
+        [Key]
         public long id { get; set; }
         public string name { get; set; }
         public string value { get; set; }
diff --git a/Server/SQL/User.cs b/Server/SQL/User.cs
index 756b50b..3326084 100644
--- a/Server/SQL/User.cs
+++ b/Server/SQL/User.cs
@@ -19,12 +19,14 @@ namespace Server.SQL
 
         public bool buyCash(long buy)
         {
+            if (buy == 0) { return true; }
             long freeCash = free_cash;
             long payCash = pay_cash;
             freeCash -= buy;
             if(freeCash < 0)
             {
-                payCash -= freeCash;
+                payCash += freeCash;
+                freeCash = 0;
             }
 
             if(payCash >= 0)
diff --git a/Server/Service/DeckChange.cs b/Server/Service/DeckChange.cs
index 719d310..b19b57c 100644
--- a/Server/Service/DeckChange.cs
+++ b/Server/Service/DeckChange.cs
@@ -8,7 +8,7 @@ namespace Server.Service
     {
         private DeckChangeReq req;
 
-        public void SaveSQL()
+        private void SaveSQL()
         {
             Statics.deckInfoSQL.SaveChanges();
         }
diff --git a/Server/Service/EquipChange.cs b/Server/Service/EquipChange.cs
index 302de4f..a9e6cf9 100644
--- a/Server/Service/EquipChange.cs
+++ b/Server/Service/EquipChange.cs
@@ -8,7 +8,7 @@ namespace Server.Service
     {
         private EquipChangeReq req;
 
-        public void SaveSQL()
+        private void SaveSQL()
         {
             Statics.equipmentrSQL.SaveChanges();
             Statics.deckUnitInfoSQL.SaveChanges();
diff --git a/Server/Service/Login.cs b/Server/Service/Login.cs
index 04c7286..6d67e51 100644
--- a/Server/Service/Login.cs
+++ b/Server/Service/Login.cs
@@ -51,7 +51,7 @@ namespace Server.Service
                 user = new User();
                 user.mail = req.mail;
                 user.uuid = Guid.NewGuid().ToString();
-                user.nickname = "NoName";
+                user.nickname = Statics.dynamicDataSQL.SelectName("defaultNick").value;
                 Statics.userSQL.Insert(user); //저장하고 유닛의 id를 얻어오기 위함.
                 #endregion
                 #region 초기 유닛 지급
diff --git a/Server/Service/NicknameChange.cs b/Server/Service/NicknameChange.cs
new file mode 100644
index 0000000..175ebad
--- /dev/null
+++ b/Server/Service/NicknameChange.cs
@@ -0,0 +1,83 @@
+using Server.System;
+using Newtonsoft.Json;
+using Server.SQL;
+using System.Text.RegularExpressions;
+
+namespace Server.Service
+{
+    public class NicknameChange : AbstractService
+    {
+        private NicknameChangeReq req;
+        private void SaveSQL()
+        {
+            Statics.userSQL.SaveChanges();
+        }
+
+        public override string Process()
+        {
+            User user = Statics.userSQL.SelectUuid(req.uuid);
+            string newNickname = req.newNickname;
+            string regular = @"^[가-힣a-zA-Z0-9\s]*$";
+            int buy;
+
+            //닉네임 체크
+            //if(!Regex.IsMatch(newNickname, regular) || (newNickname.Length < 2 || newNickname.Length > 16) || user.nickname == newNickname)
+            //{
+            //    //해당 데이터가 들어온다면 유저 정보와 같이 로그를 남기게 만들것
+            //    throw new RuntimeException("Nickname not allowed", Error.errordata);
+            //}
+
+            //가격 체크
+            if (user.nickname == Statics.dynamicDataSQL.SelectName("defaultNick").value)
+                buy = 0;
+            else
+                buy = int.Parse(Statics.dynamicDataSQL.SelectName("nicknameCash").value);
+
+            //현재 충분한 제화가 있는지 확인
+            if (!user.buyCash(buy))
+            {
+                throw new RuntimeException("Cache shortage", Error.nogold);
+            }
+
+            user.nickname = newNickname;
+
+            SaveSQL();
+            return makeResp(user);
+        }
+
+        public override Protocol ProtocolValue() => Protocol.NicknameChange;
+
+        public override Req Requst(string json)
+        {
+            req = JsonConvert.DeserializeObject<NicknameChangeReq>(json);
+            return req;
+        }
+
+        private string makeResp(User user)
+        {
+            NicknameChangeResp resp = new NicknameChangeResp();
+            resp.status = 200;
+            resp.nickname = user.nickname;
+            resp.cash = (ulong)(user.free_cash + user.pay_cash);
+            return resp.ToJson();
+        }
+    }
+
+    public class NicknameChangeReq : Req
+    {
+        public string uuid;
+        public string newNickname;
+        public override bool IsReceivedAllField()
+        {
+            if (uuid == "")
+                return false;
+            return true;
+        }
+    }
+
+    public class NicknameChangeResp : Resp
+    {
+        public string nickname;
+        public ulong cash;
+    }
+}
diff --git a/Server/System/Enums.cs b/Server/System/Enums.cs
index c560931..5dd54e0 100644
--- a/Server/System/Enums.cs
+++ b/Server/System/Enums.cs
@@ -14,6 +14,7 @@
 
     EquipChange = 200,//장비 변경
     DeckChange = 201,//덱 유닛 변경
+    NicknameChange = 202,//닉네임 변경
 }
 
 public enum Error
@@ -23,6 +24,8 @@ public enum Error
     success = 200,//성공
     notFound = 404,//프로토콜 없음
     unknown = 500,//파라미터 오류
+    errordata = 501,//잘못된 데이터
     crypto = 800,//암복호화 에러
     nodata = 900,//데이터가 없음
+    nogold = 901,//소모재화가 없음
 }
\ No newline at end of file