To prevent the generation of stay of the fuel inside of a heat insulating pipe or an intake pipe, and prevent the operation stop of an engine when the engine is inclined by the idling operation thereof by providing a ring member having a diameter smaller than that of a heat insulating pipe in the downstream of a throttle valve in an intake passage of a film type carburetor.

When a throttle valve 47 is turned to the accelerating direction, open degree of the throttle hole 47b communicated with an intake passage 16 is increased, and open degree of an injection hole 56a is increased with a rise of a needle valve 55 from the injection hole 56a of a fuel nozzle 56, and the predetermined quantity of the fuel is sucked. In a film type carburetor having such a structure, a ring member 26 having a diameter smaller than that of the heat insulating pipe 63 and made of a metal having a large heat conductivity is arranged in an outlet of an intake passage 16 so as to prevent the generation of stay of the fuel inside of the heat insulating pipe 63 or the intake pipe due to the idling operation of an engine. With this structure, flow of the air-fuel mixture is speeded up at the time of idling operation of the engine, and the generation of malfunction that the rich air-fuel mixture is flowed out at a stroke with vibration of the engine and a change of posture of the engine so as to stop the engine operation is eliminated.