PROBLEM TO BE SOLVED: To provide a moderated neutron irradiating device that can moderate neutron rays generated by a neutron source and emit neutron rays having high intensity of epithermal neutrons in spite of a reduced rate of fast neutron content.SOLUTION: A moderated neutron irradiating device 2 is equipped with moderators 21A and 21B that moderate neutron rays generated by a neutron source 5 irradiated with charged particle rays, a reflector 22 surrounding the moderators 21A and 21B, and collimator parts 24A and 24B that shape the irradiation field of the neutron rays moderated by the moderators 21A and 21B. The moderators 21A and 21B have a main body part 21A arranged on the downstream side of the neutron source 5 and an upstream part 21B arranged on the upstream side of the main body part 21A and surrounding the neutron source 5.SELECTED DRAWING: Figure 2【課題】中性子源が発生した中性子線を減速し、高速中性子の混入率が低減されていながら熱外中性子の強度が高い中性子線を出射することが可能な中性子減速照射装置を提供する。【解決手段】中性子減速照射装置２は、荷電粒子線が照射されて中性子源５が発生した中性子線を減速させる減速材２１Ａ，２１Ｂと、減速材２１Ａ，２１Ｂの周囲を囲む反射材２２と、減速材２１Ａ，２１Ｂによって減速された中性子線の照射野を整形するコリメータ部２４Ａ，２４Ｂとを備え、減速材２１Ａ，２１Ｂは、中性子源５の下流側に配置された本体部２１Ａと、本体部２１Ａの上流側に配置されて中性子源５の周囲を囲む上流部２１Ｂとを有する。【選択図】図２
