PURPOSE: To give high heater power to a heater in a car room even at low load time of an internal combustion engine, in a cooling device for the internal combustion engine constituted by assembling partly a heater core which is a heat exchanger for the heater in the car room.

CONSTITUTION: A cooling water passage is provided in a cylinder head and in a cylinder block of an internal combustion engine 10. A radiator 22, communicating with the cooling water passage, is provided. An electric motor fan 32 is provided in the vicinity of the radiator 22, also to provide a heater core 30 for a heater in a car room communicating with the cooling water passage. Warming up the internal combustion engine 10 is insufficient, and further by giving prescribed reverse rotation to the electric motor fan 32, under a condition that a flow speed in an engine room can be suppressed, in the case of turning on a heater blower S/W40, the prescribed reverse rotation is given to the electric motor fan 32.