To realize effective use of the capacity of a virtual magnetic tape and high speed access, to reduce the number of magnetic tapes and to simplify maintenance/management by installing the virtual magnetic tape of a first hierarchy and the magnetic tape of a second hierarchy in magnetic tape systems so as to manage the DB of data copying/restoring.

A copying/restoring means 13 stores data as a backup in a magnetic tape 12 from a virtual magnetic tape 11 at the time of migration, and registers and manages the corresponding relation/state of migrated data in a copying/restoring management data base 4. At the time of restoration, data is restored in the virtual magnetic tape 11 from the magnetic tape based on the state of the copying/restoring management data base 4 and data is updated. At that time, information on the presence or absence for migration from the virtual magnetic tape 11 to the magnetic tape 12, the presence or absence of the deletion of data in the virtual magnetic tape 11 and the presence or absence of restoration from the magnetic tape 12 to the virtual magnetic tape 11 are registered in the copying/restoring management data base 4.