To provide a carburetor with a fuel adjusting needle valve stable in setting.

A carburetor body has a screw-less cylindrical bore, a frusto- conical shoulder portion, a valve chamber, and an outlet flow passage which are sequentially decreased in diameter. A plastic holding member and a metallic collar are interference fitted into the screw-less cylindrical bore. The fuel adjusting needle valve has a threaded shaft portion, a screw-less valve rod, and a valve tip end portion which are sequentially decreased in an outer diameter. The threaded shaft portion is screwed in a threaded bore formed on the collar, and screwed in an axial direction shaft storing portion formed on the holding member. The shaft storing portion of the holding member has no thread at first, and the threaded shaft portion is screwed in a shaft receiving portion of the plastic holding member to form a thread groove.