A data migration method is provided which can provide a user at a low cost with a function of migrating data from an existing storage when an additional storage is installed. A business application is operated by using a business server and a first storage. When the capacity and performance of data used by a business application become insufficient, a second storage is installed to compensate for insufficiency. In this case, the management server collectively copies data and configuration information of the first storage to the second storage, the data and configuration information are deleted at a later time in accordance with migration command information selected from a GUI screen. It is therefore possible to migrate necessary data and configuration information of the first storage to the second storage, without making a user be conscious of the details of the configuration information of logical devices of a storage.