PURPOSE: To attain tracking control with high accuracy in both the reproduction and erasion modes by irradiating two light beam spots for tracking control to the positions preceding a light beam spot for record, reproduction and erasion of information on a recording medium.

CONSTITUTION: When a spot 16b is set correctly on a shift locus of a recording bit, spots 16a and 16c for tracking control are set so that about half of the beam spot diameter covers the recording bit locus at the side opposite to the shift locus. The reflected light is made incident on detectors 44aW44c through an objective lens 28 and then a beam splitter 37, a condenser lens 42 and a polarizing plate 43. The beams given from spots 16aW16c are made incident on detectors 44aW44c respectively to receive the photoelectric detection. A differential of signals is obtained between detectors 44a and 44c for tracking control. Thus the tracking control is possible with high accuracy not only in a reproduction mode but in an erasion mode. In such a way, a reproduction signal having high S/N is attained.