In an optical disk apparatus and a method for determining the recording power for the same, for determining the optimum value of a laser power when recording data onto a high density optical disk, a test signal is recorded with changing the recording power Pw while fixing an erasing power Pe. Reproduction is made on the signal recorded so as to obtain a “β” value indicative of asymmetry of the reproduction signal to each the recording power. In this instance, the “β” value, or the optimal recording power Pwo is determined, with utilizing an area or region, being called APC region, which is provided in a part of the recording regions, which are divided into a large number thereof, each being made of a predetermined information recording unit (RUB), being unique to that disk, and further equalization thereof. Herein, the erasing power Pe to be fixed is determined from a result of measurement on a modulation factor, “M” value while recoding another test signal. Or, it may be determined in accordance with strategy information, which is determined for that optical disk in advance. Or, the erasing power Pe may be determined Pe0, irrespective of the optical disks.