To provide a carburetor for stratified scavenging internal combustion engine by connecting a passage body to a conventional carburetor for supplying air separately to an engine, enabling a significant cost reduction compared with new development.

The passage body 2 having an air passage 3 is superposed on an upper wall of the carburetor body 21 having a throttle valve 43. A bolt 45 being inserted from upper half of through holes 62, 62a disposed vertically across the air passage 3 is fixed to the carburetor body 21 via a lower half of the through hole 62. The upper half of the through hole 62 is closed by a cover plate 9.