PURPOSE: To prevent fuel from being sucked out in running not needing accelerating fuel by arranging an injection nozzle for injecting the accelerating fuel in the intake side upstream of a Venturi portion in an intake path.

CONSTITUTION: Accelerating fuel is injected to an intake path 1 throgh an injection nozzle 28 which is provided at the intake side upstream of a Venturi portion 3 in the intake path 1. Also, a discharge port of the injection nozzle 28 opens to a half portion of a butterfly type throttle valve 2 opened to the intake downstream side. In acceleration an accelerating pump 20 is operated to send forcibly gasoline in a flow-out path 26 to the injection nozzle 28 and inject it to the intake path 1 through the discharge port.