a method of counting the number of tracks on an optical disk each track comprising a plurality of sectors each having an address segment and a plurality of data segments , each of the segments having at its head portion a region for recording an access code representing a track number to which the segment belongs . the method comprises the steps of sampling the access code number through an optical head , obtaining a code number difference between the present sampled access code number and the previous sampled access code number , and adding the code number difference to a track count value to obtain the number of the tracks that the optical head moves to traverse . this method can accurately and surely count the number of the tracks of an optical disk .