To prevent large thermal stress in a boundary part portion of two radiators in a radiator wherein two radiators are integrated, and an oil cooler is built in a side of first radiator for an engine.
A resistance board 16 is built in a first header tank 13 not built in with the oil cooler 40. By this, a large difference between a pressure loss in engine cooling water flowing in a longitudinal direction in a first header tank 13 built in with the oil cooler 40, and a pressure loss in engine cooling water flowing in a longitudinal direction in the first header tank 13 built in with the resistance board 16 can be prevented. Accordingly, since flowing of a large amount of engine cooling water in a first tube 11 arranged in a portion near a second tube 21, namely, an inverter cooling water side can be suppressed, a large temperature difference in a boundary part portion between an engine cooling water side and the inverter cooling water side can be suppressed.
Takahiro Miura
Fumihiro Mizuno