A disk array apparatus that is capable of effecting saving and operation of data with a simple construction. When a host computer sets "write inhibit" or "read/write inhibit" for an LDEV which is set on a first storage device, this setting is registered in an access attribute management table and is also reflected onto a migration management table. A migration control program moves the LDEV for which access limitation has been set to a lower-speed (lower-performance) second storage device or to an external storage device. When the access limitation is released, the moved LDEV is restored to the first storage device from the storage device to which the LDEV has been moved. By performing migration control in interlocking relation to control of access attributes, it is possible to obtain a simple data saving function and data management function.