To smoothly slide a throttle valve in a sliding throttle valve type carburetor in which a carburetor body is divided with the guide cylinder of the sliding throttle valve into the first body having an intake inlet and the second body having an intake outlet and the carburetor body together with an air cleaner case is screwed on an intake pipe or insulator communicating with an engine, by preventing deformation of the guide cylinder through the screwing.

A second body 6b is integrally provided with insertion pipes 19 for receiving fixing screws 3, which are parallel to an intake passage 7 and are at their tips flush with a flange face 18 of a first body 6a on the side of an air cleaner or projected from the flange face 18 toward the air cleaner. A carburetor body 6 is thus prevented from being pressed by excess force owing to the presence of the insertion pipes 19 serving as stoppers to thereby prevent an operational failure of a sliding throttle valve 10 resulting from deformation of the guide cylinder thereof.