A data migration management system for preventing alteration such as rewriting or deletion, and migrating data between storage systems during an alteration prevention term. This data migration management system copies data from a logical device of a source storage system to a logical device of a destination storage system, and sets an alteration prevention setting for the destination logical device. Once the data migration management system acquires an alteration prevention status report from the destination storage system and confirms that the data has been migrated without alteration, it cancels the alteration prevention setting of the source storage system.