diff --git a/BJD/option/OptionBasic.cs b/BJD/option/OptionBasic.cs
index 6e30d3f1..0dad2a6c 100644
--- a/BJD/option/OptionBasic.cs
+++ b/BJD/option/OptionBasic.cs
@@ -38,8 +38,8 @@ private OnePage Page1(string name, string title, Kernel kernel){
             onePage.Add(new OneVal("serverName", "", Crlf.Nextline, new CtrlTextBox(IsJp() ? "サーバ名" : "Server Name", 20)));
             onePage.Add(new OneVal("editBrowse", false, Crlf.Nextline,
                                    new CtrlCheckBox(IsJp() ? "フォルダ・ファイル選択を編集にする" : "can edit browse control")));
-            onePage.Add(new OneVal("lang", 0, Crlf.Nextline,
-                                   new CtrlComboBox(IsJp() ? "言語" : "Language", new []{"Japanese", "English"}, 80)));
+            onePage.Add(new OneVal("lang", 2, Crlf.Nextline,
+                                   new CtrlComboBox(IsJp() ? "言語" : "Language", new []{"Japanese", "English", "Auto"}, 80)));
             return onePage;
         }
 
diff --git a/BJD/util/IniDb.cs b/BJD/util/IniDb.cs
index 08d4844c..1c805340 100644
--- a/BJD/util/IniDb.cs
+++ b/BJD/util/IniDb.cs
@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.IO;
 using System.Text;
+using System.Threading;
 using Bjd.ctrl;
 using Bjd.option;
 
@@ -235,13 +236,20 @@ public void Save(String nameTag, ListVal listVal){
         // 設定ファイルから"lang"の値を読み出す
         public bool IsJp(){
             var listVal = new ListVal{
-                new OneVal("lang", 0, Crlf.Nextline,
-                           new CtrlComboBox("Language", new[]{"Japanese", "English"}, 80))
+                new OneVal("lang", 2, Crlf.Nextline,
+                           new CtrlComboBox("Language", new[]{"Japanese", "English", "Auto"}, 80))
             };
             Read("Basic", listVal);
             var oneVal = listVal.Search("lang");
-            return ((int) oneVal.Value == 0);
-
+            var bjdLangId = (int)oneVal.Value;
+            if (bjdLangId == 2/*Auto*/)
+            {
+                return (Thread.CurrentThread.CurrentUICulture.Name == "ja-JP");
+            }
+            else
+            {
+                return (bjdLangId == 0);
+            }
         }
     }
 }