PROBLEM TO BE SOLVED: To provide a particle beam irradiation apparatus enabling high-accuracy irradiation with beams in a shorter amount of time even to an affected part three-dimensionally moving by respiration or the like.SOLUTION: A particle beam irradiation apparatus 1 includes: a dose monitoring part 50 integrating signals corresponding to a dose of irradiation irradiating an irradiation target a position monitoring part 51 a gravity center position calculating part 90 calculating a gravity center position of particle beams a respiratory waveform detecting part 250 detecting a respiration status of the irradiation target as a respiratory waveform a respiration synchronization correction processing part 83 in which information for correcting a displacement amount of the irradiation-target affected part corresponding to the respiratory waveform is set and which calculates an actual irradiation position from the displacement amount of the affected part and a control part 80 controlling a plurality of irradiation spots to be collectively irradiated for every group on the basis of the displacement amount of the affected part.
