To reduce the dispersion of drive sensitivity together with the dispersion of signal sensitivity by deciding a loop gain based on an oscillation frequency of a focus error signal.

Outputs of photodetectors become their respective voltages V1-V4, which are then inputted to an FE signal generating circuit 7 in which an FE signal for showing focus displacement of a light spot is generated. This FE signal is inputted to a 1st variable gain amplifier 6 and is amplified. Then, the FE signal is subjected to a phase advancing compensation by a 1st phase compensation circuit 5. An objective lens 3a of an optical pickup 3 is moved via a focus actuator driving circuit 4 by the phase-compensated FE signal to perform a focus servo. The voltages V1-V4 are simultaneously inputted to a TE signal generating circuit 11 to generate a TE signal showing a track deviation. This TE signal is subjected to a phase lead compensation by a 2nd phase compensation circuit 9, and hence the objective lens 3a is moved to perform a track servo.