The substrate holder is a device for holding a substrate and pressing it against a polishing pad. The substrate holder includes: an inner retaining ring vertically movable independently of the top ring body and arranged around the substrate; an inner pressing mechanism to press the inner retaining ring against the polishing surface of the polishing pad; an outer retaining ring to vertically movable independently of the inner retaining ring and the top ring body; an outer pressing mechanism to press the outer retaining ring against the polishing surface; and a supporting mechanism to receive a lateral force applied to the inner retaining ring from the substrate during polishing of the substrate and to tiltably support the outer retaining ring.