To readily control an in-plane polishing velocity distribution, by providing a thermal control system at a top ring to control the temperature thereof, and controlling the in-plane thermal distribution of the surface of a semiconductor substrate which is in contact with the top ring.

Three roles of heaters 11, 12, 13 are embedded in a top ring 103A in a concentric manner with respect to a surface 10 which is in contact with a semiconductor substrate. Independently controlled three currents are supplied to these heaters 11, 12, 13 by way of three pairs of conductors 11a, 11b; 12a, 12b; 13a, 13b so as to control the calorific value of the individual heaters 11, 12, 13. When polishing the contact surface of the semiconductor substrate, an in-plane thermal distribution in the radial direction of the semiconductor substrate is controlled by the thermal control system. Considering that the polishing velocity of the semiconductor substrate is effected by the temperature of the substrate, the thermal control system consisting of the heaters 11, 12, 13 provided to the top ring 103A, ensures easy control of the in-plane average polishing velocity and the in-plane polishing velocity distribution of a film to be polished in the semiconductor substrate.