PURPOSE: To reduce the exhaust gas emission and enhance the rate of fuel consumption by furnishing an atmosphere intake pipe, which is put in communication with a divergent pipe when the temperature exceeds a certain set value, and an evaporated gas rate-of-flow control device to control by means of pressure in the divergent pipe.

CONSTITUTION: When the cooling water for engine is at a low temperature, the valve of a bimetal vacuum switching valve 38 is closed, so that the evaporated gas from the fuel in a canister 50 is not supplied to the intake system of the engine. Thus deterioration of exhaust gas emission can be prevented when the temperature is low. When the temp. of cooling water rises to exceed the set value during warming-up, the valve of switching valve 38 is opened to supply the evaporated gas in the canister 50 to the intake system. When thereafter the external air temperature has risen and the temp. of the fuel has exceeded the set value, the valve of a bimetal vacuum switch valve 14 is opened to introduce the atmosphere.