It is possible to manage an empty region in a disc partition while satisfying an inhibit matter of the ROM standard not recording a space bit map describer (SBD). The SBD is recorded upon disc initialization and additional recording into the partition is performed by using the SBD regardless of the access type in the device. When ejecting the disc, pointer information to the SBD recorded in the partition describer (PD) is hacked up in the SBD pointer information save file or save data and then the pointer information is erased. Upon disc recognition, the existence of the save file/data is confirmed and the SBD is restored.