An information recording medium includes a disk information area; a user area including a plurality of sectors; and a spare area including at least one sector which, when at least one of the plurality of sectors included in the user area is a defective sector, is usable instead of the at least one defective sector. The spare area is located radially inward from the user area. A physical sector number of a sector to which a logical sector number “0” is assigned, among the plurality of sectors included in the user area and the at least one sector included in the spare area, is recorded in the disk information area.