Abstract: A first cooling water circuit is configured such that the cooling water that has come out from the engine passes through the first intake-air cooling device and returns to the engine again. A second cooling water circuit is configured such that the cooling water that has come out from the engine passes through the second intake-air cooling device and returns to the engine again. A heat exchanger is configured to perform heat exchange between the cooling water that has come out from the engine and flowing to the first intake-air cooling device and the cooling water that has come out from the second intake-air cooling device and that is flowing to the engine.