To solve a problem, in an optical disk of a structure in which a plurality of recording layers are laminated, that the capacity of an OPC area per layer is smaller than that of an optical disk of a single-layer structure because margin is required at the boundary of the OPC area in which the OPC areas of respective recording layers are arranged so as not to overlap with each other.

In the first-time recording of the optical disk, the optimum recording power values ML1, ML2 are obtained for each of first and second layers of the optical disk by recording/reproducing a test signal using the OPC areas thereof, and the ratio ML2/ML1 thereof is stored (S2, S3). In the second-time recording or after, the optimum recording power value PL1 is obtained by recording/reproducing the test signal using the OPC area of the first layer of the optical disk (S4), and the optimum recording power value PL2 for the second layer is obtained by calculation (S5). Thus, the OPC area of the second layer is narrowed to secure the wide OPC area of the first layer, and the number of times of OPCs can be remarkably increased.