A polishing apparatus has a polishing table (12) with a polishing surface (10) attached thereon, and a top ring (20) for pressing a workpiece (W) against the polishing surface (10). The top ring (20) has a housing (40) and a retainer ring (44) vertically movable in the housing (40) for holding an outer circumferential edge of the workpiece (W). The polishing apparatus includes a vertically moving mechanism operable to vertically move the top ring (20), a bracket (28) vertically movable together with the top ring (20), a stopper (32) adjustable in vertical position to prevent downward movement of the bracket (28), and a sensor (36) for detecting a distance between the stopper (32) and the bracket (28). The polishing apparatus also includes a control unit (34) operable to adjust the stopper (32) in vertical position when the retainer ring (44) is brought into contact with the polishing surface (10) while a lower surface of the housing (40) of the top ring (20) is located, at a predetermined height from the polishing surface (10) so that the distance between the stopper (32) and the bracket (28) is equal to a difference between a height of the lower surface of the housing (40) from the polishing surface (10) at the time of polishing and the predetermined height.