A printed circuit board includes one surface on which a plurality of electronic elements are mounted, at least one of the plurality of electronic elements generating heat during its operation, a board case which accommodates the printed circuit board, a cooling cover which has an inner surface and an outer surface, and a plurality of radial cooling bodies each formed to extend from the outer surface of the cooling cover so as to be inclined upward and configured to receive the heat generated from the printed circuit board to dissipate the heat externally. The inner surface of the cooling cover is in close contact with another surface of the printed circuit board while covering the board case. Each of the plurality of radial cooling bodies includes a unit heat pipe. The unit heat pipe includes one end which is connected to the outer surface of the cooling cover and another end to which a plurality of cooling ribs are formed to extend outward in a radial direction from an outer circumferential surface of the another end of the unit heat pipe.