Before tracking control is turned on, there is determined a correction formula for correcting a balance value of a tracking error signal depending on a position of a movable lens for spherical aberration correction. Then, after the tracking control has been turned on, using an RF signal as an index, the adjustment of the position of the movable lens for spherical aberration correction is performed, while the balance value of the tracking error signal is corrected by use of the correction formula. An adjustment value for adjusting the balance value of the tracking error signal at a time point of completing the adjustment of the position of the movable lens for spherical aberration correction is stored.