If a defective cluster in a spare area is managed with a defect entry, the size of a DFL will increase as the size of the spare area increases with an increase in the number of recording layers stacked in a disc. An information recording medium according to the present invention has pointer information indicating the location of the next available cluster in each spare area, and restricts the direction in which the spare area is used. Also, a defect entry indicating a defective cluster in the spare area is registered with the DFL. Thus, even if the size of the spare area 15 increases, the size of the DFL 21 can be kept relatively small. Furthermore, even after physical reformatting is done, a defective cluster, if any, in the spare area 15 can still be recognized as a defect and the control operation can be performed so that a replacement cluster is not re-allocated to that defective cluster (i.e., the defective cluster is not used).