There is provided an optical disk device which quickly inspects the presence or absence of a defect in an optical disk in order to ensure that it can be played back on various types of optical disk devices. A detection unit uses signals supplied from a playback unit to detect defects from each of an RF signal, a focus error signal, and a tracking error signal. A CPU stores positions of the defects in a memory. The playback unit plays back data while degrading playback conditions at the positions of the defects . The detection unit detects an error rate of the played-back data, and finally determines whether the optical disk is “OK” or “NG”.