To provide a ram air supercharged type intake device which can enhance the responsiveness of an engine even though it has a CY type carburetor.

A carburetor 11 comprises an atmospheric chamber 17a communicated with the atmosphere, and a vacuum chamber 17b in which an intake vacuum downstream of a piston valve 17d is effected. With this arrangement, the piston valve 17d is opened in accordance with a pressure differential between both chambers. Further, a suction chamber pressurizing pipe 32 for guiding the pressure of ram air is connected to an atmospheric air communication port of the atmospheric chamber 17a.