To reduce re-request processing for contents data and contents attribute information accompanied with their disappearance by executing it only to either of them.

A request for backup storage is detected in a status that contents data and a contents attribute file 47 are stored in a hard disk, and either the contents data or the contents attribute file 47 is transferred to an external storage device 9 for backup storage. Thus, even when both the contents data and the contents attribute file 47 disappear once from the hard disk, their disappearance can be prevented in a status that either the contents data or the contents attribute file 47 remains in the external storage device 9. Therefore, it is possible to reduce re-request processing accompanied with their disappearance by executing it only to either of them.