In the corpuscular ray lighting system, it designates that the dose distribution whose precision is higher is given as purpose. The lighting control section (13), the energy setting controller which sets the energy of the charged particle beam (14) with, the beam scanner (41) the beam scan controller which is controlled (16) with, the beam diameter modification vessel (40 and 60) the beam diameter controller which is controlled (15) with to have, the lighting control section (13), to set beam diameter of the charged particle beam to first beam diameter the beam diameter controller (15) with, scanning the charged particle beam in step condition the beam scan controller (16) with, in the specified territory of lighting goal the charged particleIt irradiates the beam, first beam diameter it sets beam diameter of the charged particle beam to the second beam diameter which differs after that, the beam diameter controller (15) with, scanning the charged particle beam in step condition the beam scan controller (16) with, in order to irradiate the charged particle beam to the territory where it is piled up at least with the portion of the specified territory of lighting goal it controls.粒子線照射システムにおいて、より精度の高い線量分布を与えることを目的とする。照射制御部(13)は、荷電粒子ビームのエネルギーを設定するエネルギー設定制御器(14)と、ビーム走査器(41)を制御するビーム走査制御器(16)と、ビーム径変更器(40、60)を制御するビーム径制御器(15)とを備え、照射制御部(13)は、ビーム径制御器(15)により荷電粒子ビームのビーム径を第一のビーム径に設定し、ビーム走査制御器(16)により荷電粒子ビームをステップ状に走査して照射目標の所定の領域に荷電粒子ビームを照射し、その後、ビーム径制御器(15)により荷電粒子ビームのビーム径を第一のビーム径とは異なる第二のビーム径に設定し、ビーム走査制御器(16)により荷電粒子ビームをステップ状に走査して照射目標の所定の領域の少なくとも一部と重なる領域に荷電粒子ビームを照射するよう制御する。
