Energy degrader, charged particle beam emission system provided with same, and method of producing graphite film

Provided is an energy degrader having a degrading member which becomes less radioactive than known degrading members. This degrading member (11) is a graphite film. The thermal conductivity of the graphite film in the film surface direction is 1200 W/(m·K) or more, and the thickness of the graphite film is in the range of 0.1 μm to 50 μm inclusive.