The present invention provides a kind of accelerated particle irradiation unit that whole device can be made to minimize and can make assembly process shortening.Proton beam therapy device (accelerated particle irradiation unit) (1), has: cyclotron (2), generates proton beamlets； Shell (3), cylindrical shape and can rotate around rotation axis (A)； Irradiation portion (4), can be towards irradiation target illumination proton beamlets, also, direction of illumination (B) changes with the rotation of shell (3)； And guide line (5), the proton beamlets generated by cyclotron (2) are guided to irradiation portion (4), wherein, cyclotron (2) and a part of of guide line (5) accommodate in what shell (3).本發明提供一種能夠使整個裝置小型化並能夠使裝配工序縮短化的加速粒子照射裝置。質子束治療裝置(加速粒子照射裝置)(1)，具備：迴旋加速器(2)，生成質子射束；外殼部(3)，呈圓筒形狀且可繞旋轉軸線(A)旋轉；照射部(4)，可朝向照射目標照射質子射束，並且，照射方向(B)隨著外殼部(3)的旋轉而變化；及引導線(5)，將由迴旋加速器(2)生成的質子射束引導至照射部(4)，其中，迴旋加速器(2)及引導線(5)的一部份容納於外殼部(3)內。
