PROBLEM TO BE SOLVED: To provide a particle beam irradiation system of a high medical treatment throughput which shortens a period of time required for the initializing excitation at the time of the course switching for medical treatment chambers in the particle beam irradiation system having a plurality of medical treatment chambers.SOLUTION: This particle beam irradiation system includes: an accelerator 11 which performs the incidence, the acceleration and the outgoing radiation of a charged particle beam irradiation apparatus 24A, 24B and 24C which are respectively set in the plurality of medical treatment chambers 2A, 2B and 2C and a beam transporting apparatus 3 which transports the outgoing radiation of the charged particle beam from the accelerator to the irradiation apparatus. The particle beam irradiation system has switching electromagnets 7A and 7B which switch the beam trajectory of the charged particle beam in such a manner that the beam transporting apparatus 3 may transport the charged particle beam to any one of the irradiation apparatuses. The particle beam irradiation system includes a control apparatus 40 which performs a control in such a manner that when the accelerator is performing the outgoing radiation of the charged particle beam, the switching electromagnets are controlled so that the charged particle beam may be transported to the first irradiation apparatus, and when the accelerator is performing the incidence and the acceleration of the charged particle beam, the other switching electromagnet which is connected to another irradiation apparatus may be excited, and then, the demagnetization may be performed.COPYRIGHT: (C)2010,JPO&INPIT【課題】複数の治療室有する粒子線照射装置において、治療室のコース切替時の初期化励磁に掛かる時間を短縮し、高い治療スループットの粒子線照射装置を提供する。【解決手段】荷電粒子ビームを入射,加速,出射する加速器11と、複数の治療室2A,2B,2Cのそれぞれに設置する照射装置24A,24B,24Cと、加速器から出射した荷電粒子ビームを照射装置に輸送するビーム輸送装置3とを備え、ビーム輸送装置3がいずれか一つの照射装置に荷電粒子ビームを輸送するように、荷電粒子ビームのビーム軌道を切り替える切替電磁石7A,7Bを有し、加速器が荷電粒子ビームを出射しているときに、荷電粒子ビームを第1照射装置に輸送するように切替電磁石を制御
