An object of the present invention is to provide a particle beam irradiation chamber enabling a shift amount of position of patient in a positioned condition to be limited within an allowable range, even if a patient table is moved from an irradiation chamber entrance to an irradiation area after the positioning of patient is performed on a patient table outside the irradiation area for actual irradiation of particle beam. The present invention provides a particle beam irradiation chamber (20) comprising: an irradiation execution chamber 22 provided with a patient table 2 and surrounded by a shielding wall 21, wherein the patient table 2 is installed with a detachable top plate 5 and a drive device 9 for driving the top plate 5； a passage 23 provided at a side of the shielding wall 21 where a front chamber 25 is positioned in which a patient 45 is positioned relatively to the top plate 5, such that the patient 45 who has been positioned relatively to the top plate 5 can be passed in a straight line to the irradiation chamber 22 by using a carrier device 10； and a shielding door 24 located at an irradiation chamber entrance 30 in the front chamber 25 side of the passage 23, to shield the leakage of radiation to be less than a control value during irradiating particle beam.本發明之目的在獲得一種即使在實際照射粒子線時所使用之照射區域的患者台以外進行患者的定位之後，從照射室的入口朝照射區域移動，也可使患者之定位狀態的位置偏移量在容許範圍內的粒子線照射室。依據本發明之粒子線照射室20，係具備：照射執行室22，設置有患者台2，且被遮蔽壁21所包圍，前述患者台係具有拆裝自如的頂板5及驅動頂板5的驅動裝置9；通路23，係在遮蔽壁21中之將患者45相對於頂板5定位的前室25所在側，設置成相對於頂板5被定位的患者45可藉由搬運裝置10而朝照射執行室22直線通行；及遮蔽門24，在通路23中位於前室25側的照射室入口30，將照射粒子線時的外洩放射線遮蔽至管理值以下。
