Centering device, centering method and substrate processing apparatus

This invention relates to a centering device, a centering method and a board processing device using the centering technique associated therewith wherein the center of a disciform board mounted on the upper surface of a board supporting part can be caused to coincide with the center of the board supporting part with high precision. This invention comprises: a gas supplying unit that supplies a gas between the board mounted on the upper surface of the board supporting part and the board supporting part; and a gas controlling unit that controls the gas supplying unit such that the gas intervenes between the board and the board supporting part during the positioning of the board. According to this invention, the frictional force between the lower surface of the board and the upper surface of the board supporting part is reduced because of the intervention of the gas between the board and the board supporting part. As a result, the influence of the frictional force is suppressed, thereby improving the centering p