The objective is to eliminate the effect of the hysteresis of a scanning electromagnet so that there is obtained a particle beam irradiation system that realizes high-accuracy beam irradiation. There are provided a magnetic-field sensor (20) that measures the magnetic field of a scanning electromagnet (3) and an irradiation control apparatus (5) that controls the scanning electromagnet (3) based on a measurement magnetic field Bs measured by the magnetic-field sensor (20) and target irradiation position coordinates Pi of a charged particle beam (1b). The irradiation control apparatus (5) is provided with an inverse map means (22) that calculates a target magnetic field Bi, based on the target irradiation position coordinates Pi of the charged particle beam (1b) and a compensator (23) that outputs a control input Io, to the scanning electromagnet (3), for controlling the magnetic-field error Be between the target magnetic field Bi and the measurement magnetic field Bs to be the same as or smaller than a predetermined threshold value.
