To make a magneto-optical disk to have higher track density and enable stable tracking servo to be performed thereon. On an magneto-optical disk, a first groove Gv1, a second groove Gv2, and a third groove Gv3 are formed so as to be adjacently arranged. The first groove Gv1 and the second groove Gv2 are deep grooves, and the third groove Gv3 is a shallow groove. Data is recorded on six recording tracks of these three grooves and three lands between respective grooves. A CTS signal is obtained by a sum signal (A+B+C+D) of a photo-detector 6, and a push-pull signal is obtained by a difference signal (A+D)-(B+C) of a photo-detector 8.