A recording medium includes a spare area and the management information of the spare area. When a primary spare area is allocated for slipping replacement and linear replacement upon initialization, and a remaining portion of the primary spare area after slipping replacement and allocated for linear replacement after initialization are insufficient, allocating a supplementary spare area. The sizes of the primary and supplementary spare areas are determined by the number of defects generated upon initialization. The information on the sizes of the spare areas, and the remainder state information are recorded to efficiently manage the spare areas. In performing defect management, when an area that has already been linearly replaced is allocated as a supplementary spare area, defective blocks within the allocated supplementary spare area are not used for linear replacement, and the entries of a secondary defect list (SDL) with respect to the defective blocks are not changed.