To provide a particle beam irradiation device and particle beam treatment system that have a broad irradiation field, and a high-scan speed, and are miniaturized.SOLUTION: A particle beam irradiation device 1204 comprises three or more scanning electromagnets 101a, 101b, 102a and 102b that scan a beam in a mutually orthogonal vertical direction (a first direction) or horizontal direction (a second direction). In the three or more scanning electromagnets 101a, 101b, 102a and 102b, the scanning electromagnets 101a, 101b and scanning electromagnets 102a and 102b scanning in the same direction of the vertical direction or the horizontal direction are arranged in series on an advancement direction axis 103 of a beam, and the scanning electromagnets 101a, 101b, 102a and 102b installed at a location apart from an iso center 104 on the advancement direction axis 103 have smaller volume of a magnetic field application region.SELECTED DRAWING: Figure 1【課題】広照射野かつ高走査速度、かつ小型な粒子線照射装置および粒子線治療システムを提供する。【解決手段】粒子線照射装置１２０４は、互いに直交する垂直方向（第一の方向）または水平方向（第二の方向）にビームを走査する３台以上の走査電磁石１０１ａ，１０１ｂ，１０２ａ，１０２ｂを備え、３台以上の走査電磁石１０１ａ，１０１ｂ，１０２ａ，１０２ｂは、垂直方向または水平方向のうち同じ方向に走査する走査電磁石１０１ａ，１０１ｂおよび走査電磁石１０２ａ，１０２ｂがビームの進行方向軸１０３上に直列に配置され、かつ進行方向軸１０３上でアイソセンタ１０４から遠ざかる位置に設置された走査電磁石１０１ａ，１０１ｂ，１０２ａ，１０２ｂほど磁場印加領域の体積が小さい。【選択図】図１
