An optical-disk device includes a record unit recording data onto an optical disk, and a management-information-record unit configured to additionally write the latest disk-management information about the optical disk in management-information-record areas provided on the optical disk. When a first area of the management-information-record areas is short of a vacant area used to additionally write the disk-management information, the management-information-record unit records padding data in an unrecorded area of the first area, and additionally writes the disk-management information in a second area of the management-information-record areas, and wherein when the first area includes an unrecordable area where the disk-management information can be additionally written with difficulty, the management-information-record unit stops additionally writing the disk-management information in the first area, and additionally writes the disk-management information in the second area.