Metal side plates having projections are attached to fins at the ends of heat exchanger units, to thereby carry out heat exchange between cooling air flowing through spaces between the heat exchanger units, and the side plates. In comparison with a conventional radiator having no side plate, a heat exchanging area (heat radiating area) for the cooling air flowing through the spaces can be increased and, thus, a heat exchangeability (heat radiation capacity) can be enhanced in the present invention.