A particle beam irradiation apparatus includes: a beam generation unit that generates a particle beam; a beam emission control unit that controls emission of the particle beam; a beam scanning instruction unit that sequentially two-dimensionally instructs a position of the particle beam so that the particle beam is scanned across the entire slice; a beam scanning unit that two-dimensionally scans the particle beam; a respiration gate generation unit that generates a respiration gate synchronized with a respiration cycle of the patient; and a pulse generation unit that generates a predetermined number of scanning start pulses at substantially equally spaced time intervals in the respiration gate. The beam scanning instruction unit instructs to scan the entire slice by pattern irradiation based on a set dose from each of the scanning start pulses so that a scan of the same slice is repeated the predetermined number of times.