To hold a substrate so as to be suitable for a high-speed rotation by a method wherein a rotation means and a transmission means are engaged and moved, the rotation means is turned and the transmission means is moved.

A guide member 24 is attached so as to be freely rotatable in a state that it is exposed in the lower part from a housing 22 via a bearing 23A1 and a bearing 23A2 in the upper part and the lower part of the inner wall of the housing 22. A transmission member 25 as a cylindrical transmission means is arranged in the lower part of the inner wall of the guide member 24 in a state that it is coupled to the guide member 24. A rotation member 26 as a cylindrical rotation meand is arranged in a state that it is engaged with the inner wall of the transmission member 25. Then, the transmission member 25 is raised up to a first movement position which is decided by the set stroke of a piston 39A and the rotation member 24 is turned in the counterclockwise direction on a plane. As a result, a substrate can be held so as to be suitable for a high-speed rotation.