PURPOSE: To perform the proper emission corresponding to the operation by providing an electromagnetic valve for emitting the fuel adsorbed to a canister in a fuel disperse preventer in accordance to the sucked air.

CONSTITUTION: A canister 14 is conducted through an adsorbing path 17 to a fuel tank not shown thus to adsorb the fuel vapor. An emission path 15 is conducted through an electromagnetic valve 18 to the canister 14 where the other end is opened to the Venturi 16 of a suction tube 4. Said valve 18 is connected to a control circuit 19 to which the signals from a heat ray air flow sensor 8, O2 sensor 9, water temperature sensor 10 and a height switch 11 are provided thus to open the electromagnetic valve 18 in accordance to the air sucked into the suction tube 4.