PROBLEM TO BE SOLVED: To enable adjustment of the size and position of an irradiation field of an X-ray beam emitted from an X-ray generation unit with good operability.SOLUTION: An irradiation field restriction device to be connected to an X-ray generation unit, comprises: a pair of restriction blades 1 that define an opening width 15 of an opening 14 where X-rays pass through, by space between the blades； an opening width adjustment mechanism 17 that comprises an opening width adjustment shaft 3 for adjusting the opening width 15 by rotating to move the pair of restriction blades 1 in mutually anti-parallel directions； and an opening center adjustment mechanism 18 that comprises an opening center adjustment shaft 6 for adjusting the central position of the opening 14 by moving the pair of restriction blades 1 in parallel to the opening 14. The opening width adjustment shaft 3 and the opening center adjustment shaft 6 are disposed coaxially.【課題】Ｘ線発生装置から放出されたＸ線束の一対の照射野の大きさと位置を、操作性良く調整ができるようにする。【解決手段】Ｘ線発生装置に接続される照射野制限装置であって、Ｘ線が通過する開口１４の開口幅１５を互いの間隔により規定する一対の制限羽根１と、回転することにより前記一対の制限羽根１を互いに反平行に移動させ前記開口幅１５を調整する開口幅調整軸３を備えた開口幅調整機構１７と、前記一対の制限羽根１を前記開口１４と平行に移動させ前記開口１４の中心位置を調整する開口中心調整軸６を備えた開口中心調整機構１８と、を有し、前記開口幅調整軸３と前記開口中心調整軸６とが同軸に配置されている。【選択図】図２
