The gain of an amplification circuit for amplifying a tracking error signal generated from an RF signal sent from an optical pickup is adjusted according to a low-frequency component signal sent from a lowpass filter. A drive circuit drives an actuator according to a signal sent from the amplification circuit. Incidentally, in a case where a laser beam converted by an objective lens shifts from a central position of a track of an optical disk, the gain of the amplification circuit is increased according to the low-frequency component signal sent from the lowpass filter. The lens shift is corrected in such a way as to prevent a controlling force, which acts upon the actuator, from being reduced. Consequently, tracking servo can be applied in a stable state.