There is provided a particle beam irradiation apparatus which comprises: particle beam acceleration means (1) that are adapted to accelerate a charged particle beam particle beam transport means (2) that are adapted to transport a charged particle beam launched from the particle beam acceleration means (1) a scanning apparatus that is adapted to scan the charged particle beam transported by the particle beam transport means (2) and irradiation control means (14) that are adapted to control the scanning apparatus so as to irradiate the charged particle beam onto a target region including a plurality of small regions. The irradiation control means (14) are adapted to output to the scanning apparatus a first control signal for controlling the scanning apparatus so as to scan the charged particle beam over a small region serving as an irradiation subject among the plurality of the small regions, and a second control signal for controlling the scanning apparatus so as to change the small region serving as the irradiation subject to be a different small region among the plurality of the small regions.
