diff --git a/WiseOwlChat/ChatViewModel.cs b/WiseOwlChat/ChatViewModel.cs
index f365cf3..83d4fe8 100644
--- a/WiseOwlChat/ChatViewModel.cs
+++ b/WiseOwlChat/ChatViewModel.cs
@@ -65,16 +65,16 @@ public string ModelType
                 string? modelName = EnumHelper.GetDescription(openAIChat.ModelType);
                 if (modelName == null)
                 {
-                    return openAIChat.ModelType.ToString();
+                    modelName = openAIChat.ModelType.ToString();
                 }
-                return modelName;
+                return modelName.Replace("-", " ");
             }
             set
             {
                 foreach (MODEL_TYPE model in Enum.GetValues(typeof(MODEL_TYPE)))
                 {
                     string? modelName = EnumHelper.GetDescription(model);
-                    if (modelName == value)
+                    if (modelName != null && (modelName == value || modelName == value.Replace(" ", "-")))
                     {
                         openAIChat.ModelType = model;
                         OnPropertyChanged();
@@ -83,7 +83,7 @@ public string ModelType
                 }
                 if (Enum.TryParse<MODEL_TYPE>(value, out MODEL_TYPE mode))
                 {
-                    openAIChat.ModelType = (MODEL_TYPE)mode;
+                    openAIChat.ModelType = mode;
                     OnPropertyChanged();
                 }
             }
@@ -254,7 +254,7 @@ public ChatViewModel()
                 string? modelName = EnumHelper.GetDescription(model);
                 if (modelName != null)
                 {
-                    ModelTypeItems.Add(modelName);
+                    ModelTypeItems.Add(modelName.Replace("-", " "));
                 }
             }
 
@@ -411,7 +411,7 @@ private void delayedTranslation(List<Task> delayedTaskList, ConversationEntry lo
                         {
                             string instructions = "Please translate the content below into English.  " + Environment.NewLine
                                         + "---  " + Environment.NewLine + content;
-                            return openAIChat.SystemRequest(MODEL_TYPE.GPT_35_TURBO, false, instructions, (role) => role == ConversationEntry.ROLE_SYSTEM);
+                            return openAIChat.SystemRequest(MODEL_TYPE.GPT_4o_mini, false, instructions, (role) => role == ConversationEntry.ROLE_SYSTEM);
                         })
                 ));
         }
@@ -484,11 +484,11 @@ private async Task query(Action update, Action<string?>? callback, string messag
 
             if (FunctionMode)
             {
-                string? modelName = EnumHelper.GetDescription(MODEL_TYPE.GPT_35_TURBO);
+                string? modelName = EnumHelper.GetDescription(MODEL_TYPE.GPT_4o_mini);
                 if (ModelType == modelName)
                 {
                     ModelType = modelName;
-                    popupMessageAction("Changed MODEL_TYPE to GPT_35_TURBO_16K.");
+                    popupMessageAction("Changed MODEL_TYPE to GPT_4o_mini_16K.");
                 }
             }
 
@@ -616,7 +616,7 @@ private async Task _callPipeline(Action update, Action<string?>? callback, List<
                             {
                                 instruction = QueryManager.Instance.ProcessInputText(instruction);
                             }
-                            string? result = await openAIChat.SystemRequest(MODEL_TYPE.GPT_35_TURBO, false, instruction, null);
+                            string? result = await openAIChat.SystemRequest(MODEL_TYPE.GPT_4o_mini, false, instruction, null);
 
                             if (direction.DirectionName != null)
                             {
@@ -648,7 +648,7 @@ private async Task _callPipeline(Action update, Action<string?>? callback, List<
                 if (PipelineMode)
                 {
                     await ProcessQuerysAsync(querys, false, ConversationEntry.ROLE_ASSISTANT, "");
-                    await openAIChat.setConversationTitle(MODEL_TYPE.GPT_35_TURBO, update);
+                    await openAIChat.setConversationTitle(MODEL_TYPE.GPT_4o_mini, update);
                     callback?.Invoke(null);
                 }
                 else
@@ -841,7 +841,7 @@ await openAIChat.SystemRequestStreamForPipeline(update,
 
                 if (index == 0)
                 {
-                    await openAIChat.setConversationTitle(MODEL_TYPE.GPT_35_TURBO, update);
+                    await openAIChat.setConversationTitle(MODEL_TYPE.GPT_4o_mini, update);
                 }
 
                 if (IsStop)
@@ -895,7 +895,7 @@ public async Task ProcessQuerysAsync(
                 }
 
                 string instruction = QueryManager.Instance.ProcessInputText(message.Direction);
-                var task = openAIChat.SystemRequest(MODEL_TYPE.GPT_35_TURBO, action == null, instruction, (role) => role == ConversationEntry.ROLE_SYSTEM);
+                var task = openAIChat.SystemRequest(MODEL_TYPE.GPT_4o_mini, action == null, instruction, (role) => role == ConversationEntry.ROLE_SYSTEM);
                 taskList.Add(task);
             }
 
diff --git a/WiseOwlChat/Control/ChatControl.xaml.cs b/WiseOwlChat/Control/ChatControl.xaml.cs
index 9a906cc..0438091 100644
--- a/WiseOwlChat/Control/ChatControl.xaml.cs
+++ b/WiseOwlChat/Control/ChatControl.xaml.cs
@@ -48,7 +48,7 @@ public ChatControl()
 
             modelSelector.Dispatcher.BeginInvoke(new Action(() =>
             {
-                chatViewModel.ModelType = OpenAIChat.MODEL_TYPE.GPT_4o.ToString();
+                chatViewModel.ModelType = OpenAIChat.MODEL_TYPE.GPT_4o_mini.ToString();
             }), DispatcherPriority.Loaded);
 
             Instance = this;
diff --git a/WiseOwlChat/OpenAIChat.cs b/WiseOwlChat/OpenAIChat.cs
index 89a1582..9ecda6a 100644
--- a/WiseOwlChat/OpenAIChat.cs
+++ b/WiseOwlChat/OpenAIChat.cs
@@ -21,7 +21,7 @@ public class OpenAIChat
         private ConversationInfo? _conversation;
         private ObservableCollection<ConversationInfo>? ConversationInfos;
         private bool is_addCollection = false;
-        public MODEL_TYPE ModelType { get; set; } = MODEL_TYPE.GPT_4o;
+        public MODEL_TYPE ModelType { get; set; } = MODEL_TYPE.GPT_4o_mini;
         private ForbiddenExpressionChecker forbiddenExpressionChecker = new();
         public APIFunctionRegistry FunctionCallingRegistry = new();
 
@@ -49,8 +49,8 @@ public enum MODEL_TYPE
             [Description("gpt-4o")]
             GPT_4o,
 
-            [Description("gpt-3.5-turbo")]
-            GPT_35_TURBO,
+            [Description("gpt-4o-mini")]
+            GPT_4o_mini,
 
             [Description("gpt-4-turbo")]
             GPT_4_TURBO,
@@ -182,7 +182,7 @@ public void PartnerReflection()
 
                 return result;
 
-            }, MODEL_TYPE.GPT_35_TURBO, true, partnerReflectionGuidelines, (role) => role == ConversationEntry.ROLE_SYSTEM);
+            }, MODEL_TYPE.GPT_4o_mini, true, partnerReflectionGuidelines, (role) => role == ConversationEntry.ROLE_SYSTEM);
         }
 
         public void Remove(ConversationEntry conversation) 
@@ -606,7 +606,7 @@ public bool IsFuncNameSet()
                 if (!is_addCollection && _conversation != null)
                 {
                     // 会話タイトルを作成
-                    await setConversationTitle(MODEL_TYPE.GPT_35_TURBO, update);
+                    await setConversationTitle(MODEL_TYPE.GPT_4o_mini, update);
                 }
 
                 callback?.Invoke(result);
@@ -670,7 +670,7 @@ await SendMessageStreamAsync(update, null, (msg) =>
                     {
                         _conversation.Title = msg.Split(Environment.NewLine)[0];
                         _conversation.ModelType = EnumHelper.GetDescription(modelType);
-                    }, MODEL_TYPE.GPT_35_TURBO, tempRequest);
+                    }, MODEL_TYPE.GPT_4o_mini, tempRequest);
 
             is_addCollection = true;
         }