PURPOSE: To increase the number of batch-processed wafers to several times by arranging surfaces of multiple wafers held on wafer holders to be faced to the ion radiation direction in sequence.

CONSTITUTION: The first wafer 1 and the second wafer 6 are held on wafer holders 4 by wafer pressing rings 2. When a wafer pressing plate 9 is pushed up to the wafer pressing ring 2 side, the wafer is released from the ring 2, and the wafer can be fed or removed from a disk 3 under this condition. For ion implantation, the first wafer 1 is faced to the radiation direction of an ion beam, after the ion implantation to the first wafer 1 is completed, the wafer holder 5 is rotated by 180° by a stepping motor 11, the second wafer 6 is faced to the radiation direction of the ion beam, and ion implantation is continued.