diff --git a/config/OpenPNE.yml.sample b/config/OpenPNE.yml.sample
index 95d11167a..960a8712f 100644
--- a/config/OpenPNE.yml.sample
+++ b/config/OpenPNE.yml.sample
@@ -193,12 +193,15 @@ doctrine_cache_key_prefix: ""
 http_proxy: ""
 
 ####################################
-# 言語設定
+# 国際化 (I18n)
 ####################################
 
 # 対応言語
 supported_languages: ['en', 'ja_JP']
 
+# デフォルトタイムゾーン
+default_timezone: "Asia/Tokyo"
+
 ####################################
 # プラグインチャンネルサーバ設定
 ####################################
diff --git a/lib/user/opSecurityUser.class.php b/lib/user/opSecurityUser.class.php
index 9f513691d..bdc600174 100644
--- a/lib/user/opSecurityUser.class.php
+++ b/lib/user/opSecurityUser.class.php
@@ -18,9 +18,12 @@
  */
 class opSecurityUser extends opAdaptableUser
 {
+  const TIMEZONE_NAMESPACE = 'openpne/user/opSecurityUser/timezone';
+
   protected
     $authAdapters = array(),
-    $serializedMember = '';
+    $serializedMember = '',
+    $timezone = null;
 
   /**
    * Initializes the current user.
@@ -37,9 +40,39 @@ public function initialize(sfEventDispatcher $dispatcher, sfStorage $storage, $o
 
     parent::initialize($dispatcher, $storage, $options);
 
+    if (!isset($this->options['timezone']))
+    {
+      $this->options['timezone'] = null;
+    }
+    if (!isset($this->options['default_timezone']))
+    {
+      $this->options['default_timezone'] = sfConfig::get('op_default_timezone', date_default_timezone_get());
+    }
+
+    $currentTimezone = $storage->read(self::TIMEZONE_NAMESPACE);
+    $this->setTimezone(null !== $this->options['timezone'] ? $this->options['timezone'] : (null !== $currentTimezone ? $currentTimezone : $this->options['default_timezone']));
+
     $this->initializeCredentials();
   }
 
+  public function shutdown()
+  {
+    parent::shutdown();
+
+    $this->storage->write(self::TIMEZONE_NAMESPACE, $this->timezone);
+  }
+
+  public function setTimezone($timezone)
+  {
+    if ($this->timezone != $timezone)
+    {
+      $this->timezone = $timezone;
+      date_default_timezone_set($timezone);
+
+      $this->dispatcher->notify(new sfEvent($this, 'user.change_timezone', array('timezone' => $timezone)));
+    }
+  }
+
   public function getMemberId()
   {
     return $this->getAttribute('member_id', null, 'opSecurityUser');
@@ -252,6 +285,7 @@ public function login($memberId = null)
       }
 
       $this->setCulture($this->getMember()->getConfig('language', sfConfig::get('sf_default_culture')));
+      $this->setTimezone($this->getMember()->getConfig('time_zone', sfConfig::get('op_default_timezone')));
 
       return $uri;
     }
diff --git a/lib/util/opDoctrineRecord.class.php b/lib/util/opDoctrineRecord.class.php
index 2803fa6cd..d2c86abb3 100644
--- a/lib/util/opDoctrineRecord.class.php
+++ b/lib/util/opDoctrineRecord.class.php
@@ -78,6 +78,13 @@ protected function checkIsDatetimeField($fieldName)
     return 'datetime' === $definition['type'];
   }
 
+  protected function checkIsDatetimeOrTimestamp($fieldName)
+  {
+    $definition = $this->_table->getColumnDefinition($fieldName);
+
+    return ('datetime' === $definition['type'] || 'timestamp' === $definition['type']);
+  }
+
   protected function _set($fieldName, $value, $load = true)
   {
     // In setter, empty value must be handled as opDoctrineRecord::UNDEFINED_DATETIME
@@ -85,6 +92,17 @@ protected function _set($fieldName, $value, $load = true)
     {
       $value = self::UNDEFINED_DATETIME;
     }
+    elseif ($this->checkIsDatetimeOrTimestamp($fieldName) && $time = strtotime($value))
+    {
+      $timezone        = date_default_timezone_get();
+      $defaultTimezone = sfConfig::get('op_default_timezone', 'Asia/Tokyo');
+      if ($timezone !== $defaultTimezone)
+      {
+        date_default_timezone_set($defaultTimezone);
+        $value = date('Y-m-d H:i:s', $time);
+        date_default_timezone_set($timezone);
+      }
+    }
 
     return parent::_set($fieldName, $value, $load);
   }
@@ -117,7 +135,20 @@ public function _get($fieldName, $load = true)
     // In getter, opDoctrineRecord::UNDEFINED_DATETIME must be handled as null
     if ($this->checkIsDatetimeField($fieldName) && in_array($value, array(self::UNDEFINED_DATETIME, self::UNDEFINED_DATETIME_BC), true))
     {
-      $value = null;
+
+      return null;
+    }
+    elseif ($this->checkIsDatetimeOrTimestamp($fieldName) && $value)
+    {
+      $timezone        = date_default_timezone_get();
+      $defaultTimezone = sfConfig::get('op_default_timezone', 'Asia/Tokyo');
+      if ($timezone !== $defaultTimezone)
+      {
+        date_default_timezone_set($defaultTimezone);
+        $time = strtotime($value);
+        date_default_timezone_set($timezone);
+        $value = date('Y-m-d H:i:s', $time);
+      }
     }
 
     return $value;