A substrate holding apparatus holds a substrate such as a semiconductor and presses the substrate against a polishing surface. The substrate holding apparatus includes a top ring body (2) for holding the substrate, a plurality of fluid passages (33, 34, 35, 36) for supplying a fluid to a plurality of pressure chambers (22, 23, 24, 25) defined in the top ring body, and a plurality of sensors (S1, S2, S3, S4) disposed in the fluid passages, respectively, for detecting flowing states of the fluid which flows through the fluid passages.