To equalize a gain property of a focus servo system and a tracking servo system to a gain property in which the optical disk is rotated with the reference rotation speed even though rotation speed of the optical disk is increased, in an inspection apparatus of the optical disk.

An objective lens displacement quantity detector 33 detects displacement quantity of the objective lens 25 by a focus actuator 31 and a tracking actuator 32. Feedback signal generating circuits 64, 65, phase compensating circuits 67, 68, and adders 52, 55 perform feedback compensation in accordance with the detected displacement quantity for focus servo control and tracking servo control in accordance with a position of a light spot of on the optical disk Dk detected by a photodetector 28. In this feedback compensation, feedback quantity is controlled in accordance with detecting rotation speed of the optical disk DK by an encoder 11a and a controller 50.