The objective of the present invention is to eliminate noise caused by driving a ridge filter and to achieve a uniform dose distribution without making a patient sense discomfort or anxiety. There are provided a ridge filter having a thickness distribution in which the energy that a charged particle beam loses differs depending on the position thereon through which the charged particle beam passes, a deflector that deflects the charged particle beam, and a controller that controls the deflector in such a way that the charged particle beam passes through the thickness distribution of the ridge filter.
