There is provided a particle beam irradiation apparatus that enlarges the dose distribution of beam spots, while suppressing the maximum available range of a charged particle beam from decreasing. In a particle beam irradiation apparatus including particle beam acceleration means (1), particle beam transport means (2), a scanning apparatus having a charged particle beam scanning electromagnet and a scanning power source (11), and irradiation control means (14), the scanning apparatus includes first scanning means (3) that scan a charged particle beam so as to form a pseudo-enlargement spot and second scanning means (4) that make the position of the pseudo-enlargement spot coincide with a target region and performs scanning.
