PURPOSE: To obtain large driving force with a small magnet by protruding the magnet in a tracking operation correction direction from both the side faces of a lens holder and orienting the magnetizing direction to a vertical direction to this protruding direction.

CONSTITUTION: The protruding parts are disposed on the right and left side faces of the holder 6 holding the objective lens 1 and a magnet 2 is bonded thereto. A yoke 3 is disposed on the opposing faces of the respective faces in which the magnet 2 is magnetized, a focusing coil 4 is wound thereon and a tracking coil 5 is fixed thereon. Then, according to electromagnetic force between magnetic force generated by the magnet 2 and the yoke 3 and a current passing through a coil 45, the driving force of a focusing direction and a tracking direction is obtained.