Test signals are sequentially generated. A laser beam inclusive of the generated test signals is applied to a preset test recording area in a disc-shaped recording medium to record the generated test signals thereon. A recording power of the applied laser beam is changed stepwise from a lowest level to a highest level through different intermediate levels. The lowest level, the highest level, and the intermediate levels the recording power of the applied laser beam takes are assigned to the test signals respectively. The recorded test signals are reproduced from the preset test recording area in the disc-shaped recording medium. An optimum value of a laser-beam recording power is decided on the basis of the reproduced test signals and at least one of the lowest level, the highest level, and the intermediate levels.