Abstract: An optical head which can be rotated about the rotation center by a magnetic force. There is a photodetector which is divided into a plurality of detection regions and as the optical head rotates, different detection regions are examined to determine a tracking error. Rotating between the inner and outer peripheral portions of an optical disk, the optical head selects a track on the optical disk on which information is recorded, radiates a light beam focused on the selected track, receives the light beam reflected by the optical disk to a second photodetector having three divided parallel sensor segments, and reproduces the information recorded on the optical disk.