a radiator including : a plurality of radiation fins ; and a radiation fin support base having a heater element mounted to one surface thereof and a plurality of parallel fin grooves to which the radiation fins are installed and a projection configured to fix the radiation fin formed to the other surface thereof , wherein a top of the projection pushes one side surface of the radiation fin to push the other side surface of the radiation fin toward a side surface of the fin groove , and wherein the fin groove and the projection are each divided in a plurality of pieces in a longitudinal direction of the fin groove , and each of the divided fin grooves and each of the divided projections have a same length in the longitudinal direction of the fin groove and are paired with each other .