Provided is a particle beam energy alteration device capable of altering energy in a high speed with less noise, wherein a first energy alteration unit and a second energy alteration unit for altering energy of a passing particle beam by changing a thickness of a decaying body for decaying the energy of the particle beam are such arranged that the particle beam passes the first energy alteration unit and the second energy alteration unit, and the maximum value of a decaying volume of the first energy alteration unit is smaller than that of the second energy alteration unit.本發明提供一種能夠高速地變更能量且噪音少的粒子線能量變更裝置。使衰減粒子線的能量之衰減體的厚度改變,藉以使通過的粒子線的能量改變的第一能量變更器與第二能量變更器,係以粒子線通過第一能量變更器與第二能量變更器的方式配置,並且將第一能量變更器的衰減量的最大值,設定為小於第二能量變更器的衰減量的最大值。1...粒子線2...第一能量變更器3...第二能量變更器10...能量變更置換控制器11...能量變更後之粒子線12...能量變更指令部21...第一能量變更控制器31...第二能量變更控制器
