HEAT EXCHANGER

PROBLEM TO BE SOLVED: To enhance the productivity of a heat exchanger configured so as to be capable of exchanging heat among three kinds of fluids.SOLUTION: A coolant-side header tank 62 and a cooling-water-side header tank 72, which allow a coolant tube 61 and a cooling-water tube 71 to be connected to them respectively, are configured with plate header members 621, 721, connecting intermediate plate members 622, 722, closing intermediate plate members 623, 723, and tank header members 624, 724. In this case, the states of connections between the interior of both tubes 61, 71 and the interior cavities of both header tanks 62, 72 are adjusted using such a simple configuration that some of the first and second fluid passage holes for allowing the coolant and cooling water to pass therethrough are formed in the connecting intermediate plate members 622, 722 and closed using the closing intermediate plate members 623, 723.