Index: branches/version-2_12-dev/html/install/index.php
===================================================================
--- branches/version-2_12-dev/html/install/index.php	(revision 22796)
+++ branches/version-2_12-dev/html/install/index.php	(revision 22818)
@@ -198,10 +198,12 @@
 
         //マスターデータのキャッシュを削除
-        $cache_dir = '../../data/cache/';
+        $cache_dir = DATA_REALDIR . 'cache/';
         $res_dir = opendir($cache_dir);
         while ($file_name = readdir($res_dir)){
             //dummy以外は削除
             if ($file_name != 'dummy'){
-                unlink($cache_dir . $file_name);
+                if (is_file($cache_dir . $file_name)) {
+                    unlink($cache_dir . $file_name);
+                }
             }
         }