Patent ID: 6980496

Claim:
An information recording/reproducing apparatus comprising: an optical device which irradiates light beams, including one main beam and at least two sub-beams, with respect to an information recording medium on which information recording tracks and guide tracks are alternately formed; a photo-detector which receives return lights of the main beam and sub-beams from the information recording medium to output light detection signals; and a calculation unit which produces a tracking error signal indicating an irradiation position of the main beam with respect to the information recording track and a position information signal indicating a position of the main beam relative to an alignment direction of the information recording tracks and the guide tracks on the information recording medium, based on the light detection signals, wherein the optical device irradiates two sub-beams on one of the guide tracks adjacent to the information recording track, on which the main beam is being irradiated, at positions respectively shifted by equal quantities from the center of the one guide track, and irradiates two sub-beams on the other of the guide tracks adjacent to the information recording track, on which the main beam is being irradiated, at positions shifted from the center of the other guide track by equal quantities.