diff --git a/data/class/SC_Initial.php b/data/class/SC_Initial.php
index aa25b299b2..f57c908dc9 100644
--- a/data/class/SC_Initial.php
+++ b/data/class/SC_Initial.php
@@ -83,10 +83,10 @@ class SC_Initial
      */
     public function defineDSN()
     {
-        if (defined('DB_TYPE') && defined('DB_USER') && defined('DB_PASSWORD')
-            && defined('DB_SERVER') && defined('DB_PORT') && defined('DB_NAME')
+        if (defined('DB_TYPE') && defined('EC_DB_USER') && defined('EC_DB_PASSWORD')
+            && defined('EC_DB_SERVER') && defined('EC_DB_PORT') && defined('EC_DB_NAME')
         ) {
-            $dsn = DB_TYPE . '://' . DB_USER . ':' . DB_PASSWORD . '@' . DB_SERVER . ':' . DB_PORT . '/' . DB_NAME;
+            $dsn = DB_TYPE . '://' . EC_DB_USER . ':' . EC_DB_PASSWORD . '@' . EC_DB_SERVER . ':' . EC_DB_PORT . '/' . EC_DB_NAME;
             /** サイト用DB */
             // ここで生成した DSN は使用せず, SC_Query のコンストラクタでパラメータを設定する.
             define('DEFAULT_DSN', $dsn);
diff --git a/data/class/SC_Query.php b/data/class/SC_Query.php
index 32bed1b153..8c9725e4ed 100644
--- a/data/class/SC_Query.php
+++ b/data/class/SC_Query.php
@@ -53,12 +53,12 @@ class SC_Query
         if ($dsn == '') {
             $dsn = array(
                 'phptype'  => DB_TYPE,
-                'username' => DB_USER,
-                'password' => DB_PASSWORD,
+                'username' => EC_DB_USER,
+                'password' => EC_DB_PASSWORD,
                 'protocol' => 'tcp',
-                'hostspec' => DB_SERVER,
-                'port'     => DB_PORT,
-                'database' => DB_NAME,
+                'hostspec' => EC_DB_SERVER,
+                'port'     => EC_DB_PORT,
+                'database' => EC_DB_NAME,
             );
         }
 
diff --git a/data/class/db/SC_DB_DBFactory.php b/data/class/db/SC_DB_DBFactory.php
index 498002b209..0703a2e2ef 100644
--- a/data/class/db/SC_DB_DBFactory.php
+++ b/data/class/db/SC_DB_DBFactory.php
@@ -66,12 +66,12 @@ class SC_DB_DBFactory
         if (empty($dsn)) {
             if (defined('DEFAULT_DSN')) {
                 $dsn = array('phptype'  => DB_TYPE,
-                             'username' => DB_USER,
-                             'password' => DB_PASSWORD,
+                             'username' => EC_DB_USER,
+                             'password' => EC_DB_PASSWORD,
                              'protocol' => 'tcp',
-                             'hostspec' => DB_SERVER,
-                             'port'     => DB_PORT,
-                             'database' => DB_NAME
+                             'hostspec' => EC_DB_SERVER,
+                             'port'     => EC_DB_PORT,
+                             'database' => EC_DB_NAME
                              );
             } else {
                 return '';