A polishing cloth mounted on a turntable is dressed by bringing a dresser in contact with the polishing cloth for restoring the polishing capability of the polishing cloth. The dressing is performed by measuring heights of a surface of the polishing cloth at radial positions of the polishing cloth in a radial direction thereof determining a rotational speed of the dresser with respect to a rotational speed of the turntable on the basis of the measured heights, and dressing the polishing cloth by pressing the dresser are rotating. The dresser has an annular diamond grain layer or an annular SiC layer.