To provide a stratified scavenging two-stroke engine which will not sacrifice the maximum output of the engine, makes exhaust emission clean, and is excellent in transient responsiveness such as fuel consumption saving and sudden acceleration.

In an air leading type stratified scavenging two-stroke engine, only air is introduced into a scavenging passage 7 of the engine, air-fuel mixture is introduced into a crank chamber 18 of the engine, in scavenging the engine, air in the scavenging passage 7 is led to discharge exhaust gas of a combustion chamber 4, and then the air-fuel mixture is supplied to the combustion chamber 4. An air control valve 35 for controlling the area of the air passage 36 interlocking with throttle valve 48 of a carburetor is provided between the scavenging passage 7 of the engine and the air passage 46 of the carburetor.