This charged particle beam irradiation device (1) comprises: a cyclotron (3) which accelerates charged particles and emits a charged particle beam (P) a vacuum duct (7) which transports the charged particle beam (P) emitted from the cyclotron (3) to an irradiation nozzle (5) an extension duct (10) which is disposed inside the irradiation nozzle (5) on the propagation path of the charged particle beam, has an interior filled with inert gas, and is provided with Kapton films (13, 14) at an inlet and an outlet, the Kapton films transmitting the charged particle beam (P) a gas supply unit (20) which supplies helium gas to the interior of the extension duct (10) a scanning magnet (12) which is disposed around the extension duct (10) and scans the charged particle beam (P) and a leak valve (36) which leaks helium gas in the extension duct (10) to the outside when the internal pressure of the extension duct (10) is greater than or equal to a set pressure. The gas supply unit (20) has supply lines (A-C) having different amounts of helium gas supply.提供能夠藉由簡單的構成來管理對筒體之惰性氣體供給量之帶電粒子束照射裝置。本發明的帶電粒子束照射裝置(1)具備有:迴旋加速器(3),加速帶電粒子而射出帶電粒子束(P);真空導管(7),向照射噴嘴(5)輸送從迴旋加速器(3)射出之帶電粒子束(P);延長導管(10),在照射噴嘴(5)內配置於帶電粒子束的進路上,內部填充有惰性氣體,並且在入口及出口處具有,使帶電粒子束(P)透過之聚醯亞胺薄膜(13、14);氣體供給部(20),向延長導管(10)內供給氦氣;掃描磁鐵(12),配置於延長導管(10)的周圍,且掃描帶電粒子束(P);及漏洩閥(36),當延長導管(10)的內部壓力為設定壓以上時,使延長導管(10)內的氦氣洩漏到外部;氣體供給部(20)具有氦氣供給量分別不同之供給管線(A~C)。6‧‧‧射束輸送管線7‧‧‧真空導管8‧‧‧偏轉磁鐵13、14‧‧‧聚醯亞胺薄膜10‧‧‧延長導管10a‧‧‧入口部10b‧‧‧中央部10c‧‧‧出口部20‧‧‧氣體供給部22‧‧‧氦氣容器23‧‧‧供給管24‧‧‧氣體容器側配管25‧‧‧導管側配管26‧‧‧第1配管27‧‧‧第2配管28‧‧‧第3配管29、30、31‧‧‧閥32‧‧‧三通閥33‧‧‧吸引泵34‧‧‧吸引配管35‧‧‧切換閥36‧‧‧漏洩閥37‧‧‧壓力計P‧‧‧帶電粒子束He‧‧‧氦氣A‧‧‧壓力維持用供給管線B‧‧‧調整用供給管線C‧‧‧置換用供給管線
