PURPOSE: To enhance the reliability in a semiconductor device by securing a high polishing speed and uniformity in the surface and performing polishing while the damage to the substrate is suppressed, and applying the technique to the flattening in the manufacturing process of the semiconductor device.

CONSTITUTION: After a substrate is polished halfway through a desired amount under the polishing conditions where mechanical polishing is predominant, polishing conditions are switched to those where chemical polishing is predominant and polishing is made to a desired amount. With the switching in the polishing conditions, mechanical polishing force is reduced by decreasing polishing pressure and decreasing the hardness of polishing particles and chemical polishing force is increased by increasing the surface temperature of a rotary surface plate 23 by a heater 28, increasing the temperature of an abrasive 22 to be supplied, and switching the polishing particles to those with a high affinity with a surface to be polished of the substrate.