PURPOSE: To improve the yield rate in manufacturing without damaging a wafer, by supporting pawls which support the end surface of the wafer at least at three or more points on the main body of a chuck so that the pawls can be opened and closed.

CONSTITUTION: A spot facing 13 for accommodating a wafer 10 is provided in a wafer mounting susceptor 11. A pawl guide groove 12 for guiding palws 3 of a main body 1 of a chuck is provided so as to face the position of the end surface of the wafer in the spot facing 13. An operating plate 2 is turned in the counterclockwise direction, and the pawls 3 of the main body 1 of the chuck are opened. The pawls 3 are made to face the position of the end surface of the wafer 10 from the outside. Then, the operating plate 2 is turned in the clockwise direction, and the pawls 3 are closed and brought into contact with the end surface of the wafer 10. The end surface of the wafer 10 is supported with the pawls 3 at three points. Thus, the wafer can be set on the susceptor accurately.