Each record of a file recording management table has three fields: Type, Contents, and Next Record Number. The Type field indicates whether the record is a “file name record” that has file name information in the Contents field or a “consecutive recording area record” that has position information on a consecutive recording area (position information on a positionally consecutive recording area) of file data in the Contents field. The records are linked and are recorded in one physical recording area as one file recording management table.