A stacked conformation radiotherapy system capable of homogenizing a radiation dose distribution, including an irradiation head and irradiation control means. The irradiation head projects a particle beam accelerated by an accelerator, toward an object to-be-irradiated, and it includes wobbler electromagnets for deflecting and scanning the particle beam. In carrying out stacked conformation radiotherapy by deflecting and scanning the particle beam, the irradiation control means subjects the wobbler electromagnets to magnetization controls so that the particle beam may depict a one-stroke revolving orbit which begins with a start point and returns to the start point, and it performs a control so that the irradiation period of the particle beam to be outputted from the irradiation head may become integral times a wobbler cycle which is required for the particle beam to make one revolution of the revolving orbit.