A particle radiation monitoring apparatus according to one aspect of the present invention includes a detecting unit to detect radioactive ray information of braking radiation from electrons undergoing action of particle beams incident on an irradiation body in accordance with a positional relation with the irradiation body and a calculating unit to calculate information on behaviors of the particle beams in the irradiation body from the radioactive ray information of the braking radiation corresponding to the positional relation that is detected by the detecting unit.
