An optical disk recording/reproducing apparatus for accurately determining optimum recording power of a laser beam even if medium deviations occurs, stabilizing recording quality, and realizing recording which hardly causes read inability error. In test recording, a laser drive (5) irradiates a laser beam to an optical disk (1) to record information while varying the recording power stepwise and reproduce the information stepwise recorded on the optical disk. A recorded state index value calculating unit (9) determines the value representing the index of the recorded state from the signal level of the reproduced information at each step. A smoothing calculating unit (11) performs smoothing calculation of the recorded state index value at each step. An optimum recording power determining unit (12) determines the optimum power by acquiring the optimum value from the recorded state index values at the steps after smoothing calculation to record information on the optical disk with the optimum power determined in recording.