To use a heat exchanger as a vehicular oil cooler.

An oil cooler is provided with an oil cooler housing 22 and a coolant hose connector 24 for transferring coolant flow between the oil cooler housing 2 and a coolant hose. A hose connector 24 is formed in such a constitution that the direction of coolant flow is deviated at a prescribed angle, and provided with a first opening 60 formed on the oil cooler housing 22, and a tube member 30 as an integrated piece. The tube member provided with a coolant opening formed at a position in close proximity to its first end 32 due to transferring coolant flow, is formed,in such a constitution that a second end 34 thereof is connected to a coolant hose 28, a flange is formed around one of the first opening 60 and coolant opening, and the flange is accepted to the other side in the first opening 60 and the coolant opening.