To always make the suitable amount of fuel particulate by providing a main jet and a check valve in a fuel passage from a constant fuel chamber to a main nozzle and by providing a pipe having nozzle ports on the surface thereof and extending the nozzle in the direction across the narrowest venturi portion.

When the pressure of the main nozzle 23 side of a fuel passage 11 is lower than a constant fuel chamber 5, the valve element 19 of a check valve 14 contacts a stopper 20 to open a valve passage 18 and to send the fuel of the amount regulated by the orifice 12a of a main jet 12 to the main nozzle 23. An air bleed passage 21 is joined to the downstream of the check valve 14 of the fuel passage 11 and bleed air measured by a bleed jet 22 is supplied thereto. The main nozzle 23 has a plurality of nozzle ports 25 opening to the downstream of the intake air flow on the surface of a pipe crossing the narrowest venturi portion and hence can supply particulate fuel to an engine.