In a charged particle beam irradiation apparatus to be adapted to a particle beam cancer treatment system or the like, a desired depth dose distribution is highly precisely created. In the charged particle beam irradiation apparatus that irradiates a particle beam, which is radiated from a particle beam generation unit, to a subject to be irradiated via a ridge filter exhibiting a cyclic thickness distribution for causing the particle beam to exhibit a desired energy distribution, the ridge filter has plural ridges thereof arranged to be perpendicular to entering directions of the particle beam.