A radiation monitor includes a radiation detection unit detecting radiation, and an optical fiber transmitting photons emitted from a light emitting element of the radiation detection unit, wherein the radiation detection unit includes a first light emitting element generating a photon in response to incident radiation, a chemical compound part having chemical compounds which generate charged particles by nuclear reactions with incident neutrons, and a second light emitting element being located between the first light emitting element and the chemical compound part and generating a photon in response to radiation.