PURPOSE: To keep a distance from an optical pickup to a disk constant on both A and B sides by adjusting the height of a fulcrum at a supporting mechanism to support the optical pickup movably in the direction of a disk diameter.

CONSTITUTION: In order to keep the distance from an optical pickup 4 to a disk D constant on the both A and B sides, an adjusting mechanism 16 is provided to vertically move the turning fulcrum point, namely, a support shaft 14 of an upside supporting mechanism part 6 corresponding to the B side so as to separate it from the disk D. Therefore, the height of the upside supporting mechanism part 6 corresponding to the B side of the disk D can be varied. Thus, the distance between the optical pickup 4 and the disk D in the state of supporting the optical pickup 4 by the upside supporting mechanism part 6 can be adjusted equal to the distance in the state of supporting the optical pickup 4 by a downside supporting mechanism part 5 corresponding to the A side of the disk D.