To improve responsiveness of fuel supply control, a rotary carburetor 100 has a nozzle 8 including a fuel discharge port 8a and a needle 10 disposed coaxially with the nozzle 8 and disposed with a portion inserted into the nozzle 8. The needle 10 can be displaced relative to the nozzle 8 to change an effective area of the fuel discharge port 8a. The rotary carburetor 100 has an electric motor 14 for displacing the needle 10 along an axis, and a drive mechanism component 12 interposed between the electric motor 14 and the needle 10 and converting a rotational movement of the electric motor into a linear movement.