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 formed by applying nitriding process to either a chrome- molybdenum steel or a stainless steel. For the jet needle 17, a material subjected to a nickle-boron plating process, or eutectoid ceramic fine-particles or diamond super fine-particles a nickle-phosphorous plating processed film, or either a chrome-molybdenum steel or a stainless steel subjected to a nitriding process, or a ferrous material subjected to a nitriding coating process is used.