An energy degrader includes: a damping unit that attenuates energy of incident charged particles and has a thickness changing stepwise or continuously according to a position of a two-dimensional coordinate system within a plane crossing a traveling direction of charged particles and a driving unit that performs translational driving of the damping unit in first and second axial directions that are directions of two axes crossing each other in the two-dimensional coordinate system.本發明提供一種能夠謀求裝置的小型化之降能器及具備該降能器之帶電粒子照射系統。將厚度階梯性或連續性不同的部份(11)作為衰減能量之衰減部(12),二維配置在與帶電粒子的前進方向交叉之面上。並且,降能器(10)設為具備向在二維座標系上交叉之第1軸向X及第2軸向Y並進驅動衰減部(12)之驅動手段(40)之結構。能夠藉由利用二維配置之衰減部縮小衰減部的最大外形。藉此,能夠謀求裝置的小型化。並且,能夠藉由同時向2軸向移動衰減部,縮短移動時間並縮短能量衰減量的調整時間。10...降能器40...驅動機構48...驅動馬達47a...螺母47...滾珠螺桿46...第2直線導軌12...衰減部11...衰減材料塊45...驅動用框架44...驅動馬達43a...螺母49...基座框架43...滾珠螺桿42...第1直線導軌41...固定用框架X...第1軸向Y...第2軸向
