diff --git a/Config/Migration/1769652195_add_index.php b/Config/Migration/1769652195_add_index.php
new file mode 100644
index 0000000..9d89bd2
--- /dev/null
+++ b/Config/Migration/1769652195_add_index.php
@@ -0,0 +1,57 @@
+<?php
+/**
+ * インデックス追加のみ。
+ *
+ * @package Researchmap\RmNetCommons\Config\Migration
+ */
+class AddIndex extends CakeMigration {
+
+/**
+ * Migration description
+ *
+ * @var string
+ */
+	public $description = 'add_index';
+
+/**
+ * Actions to be performed
+ *
+ * @var array $migration
+ */
+	public $migration = array(
+		'up' => array(
+			'create_field' => array(
+				'content_comments' => array(
+					'indexes' => array(
+						'idx1_p_content_comments' => array('column' => array('block_key', 'plugin_key','content_key','status'), 'unique' => 0),
+					),
+				),
+			),
+		),
+		'down' => array(
+			'drop_field' => array(
+				'content_comments' => array('indexes' => array('idx1_p_content_comments')),
+			),
+		),
+	);
+
+/**
+ * Before migration callback
+ *
+ * @param string $direction Direction of migration process (up or down)
+ * @return bool Should process continue
+ */
+	public function before($direction) {
+		return true;
+	}
+
+/**
+ * After migration callback
+ *
+ * @param string $direction Direction of migration process (up or down)
+ * @return bool Should process continue
+ */
+	public function after($direction) {
+		return true;
+	}
+}