A front surface of the wafer is contacted with a straight-shaped front surface cleaning brush, and a pressure is applied on the front surface cleaning brush from both ends to enlarge the diameters in both end portions of the front surface cleaning brush. The front surface cleaning brush rotates with a shaft being an axis. An inner surface of the front surface cleaning brush is directly in contact with a surface of the shaft. The front surface cleaning brush is composed of a single structure made of synthetic resin.