A radiation shielding unit for a nuclear reactor is disclosed. The radiation shielding unit for the nuclear reactor shields radiation generated from the nuclear reactor. The radiation shielding unit includes a first metal sheet which is composed of a metal thin film to shield gamma rays; and a second metal sheet which is composed of a metal thin film to shield neutrons. The radiation shielding unit is formed by alternately arranging a plurality of first metal sheets and a plurality of second metal sheets.
