PURPOSE: To provide a carburetor fuel metering device having less change with the lapse of time in fuel metering accuracy and having excellent durability.

CONSTITUTION: In a fuel metering device composed of a jet needle 17 for fuel metering and a needle jet 18 for fuel injection, the material and the process of the jet needle 17 and the needle jet 18 are combined and used as follows: The needle jet 18 is composed by applying nickle-boron plating process. For the jet needle 17, 440 series stainless steel of martensite series subjected to a quenching process or a nickle-boron process, or either eutectoid ceramic fine-particles or eutectoid diamona super fine-particles in a nickle-phosphorous plating processed film, is used.