PROBLEM TO BE SOLVED: To provide a particle beam therapy system capable of accurately irradiating an affected area with a particle beam even if the fixed position of the affected area or the state of internal organs is different from a treatment plan formulated in advance. According to an embodiment, a CT device 2 which is a three-dimensional image acquisition unit installed in a treatment room and acquires a three-dimensional image of the body on the day of treatment, and a dose distribution based on the three-dimensional image acquired on the day of treatment. Based on the dose distribution display device 42, which is a dose distribution display unit that displays the dose distribution of the pre-planned treatment plan data, the dose distribution based on the three-dimensional image of the day of treatment, and the dose distribution of the pre-planned treatment plan data. The treatment management device 43, which is a selection unit for selecting whether or not to change the treatment plan data, and the scanning unit, which is an irradiation unit for irradiating the affected area with a particle beam based on the treatment plan data based on the selection in the treatment management device 43. It includes an irradiation device 1. [Selection diagram] Fig. 3【課題】患部の固定位置又は体内臓器の状態があらかじめ立案した治療計画と異なっていても、患部に正確に粒子線ビームを照射することのできる粒子線治療システムを提供する。【解決手段】実施形態によれば、治療室に設置されて治療当日の体内３次元画像を取得する３次元画像取得部であるＣＴ装置２と、治療当日に取得した３次元画像による線量分布と、あらかじめ立案された治療計画データの線量分布とを表示する線量分布表示部である線量分布表示装置４２と、治療当日の３次元画像による線量分布及びあらかじめ立案された治療計画データの線量分布に基づいて、治療計画データを変更するか否かを選択する選択部である治療管理装置４３と、治療管理装置４３での選択に基づく治療計画データによって患部に粒子線ビームを照射する照射部であるスキャニング照射装置１と、を備える。【選択図】図３
