To provide an alcohol combined-use type carburetor easily achieving an appropriate air-fuel ratio at low cost even if many different types of fuels having a different alcohol mixture ratio with respect to gasoline are used.

In this alcohol combined-use type carburetor 10, fuel stored in a constant fuel chamber 104 is mixed with outside air routed through an air bleed passage while being fed by a main fuel passage 100 and supplied from a main nozzle 101 to an intake passage 2. An additional fuel passage 102 for adding fuel to the normal amount of fuel supply extends from the constant fuel chamber 104, and a flow rate regulating means having a regulating valve 108 for regulating the flow rate of the additional fuel is disposed in the middle of the additional fuel passage 104. The opening of the regulating valve 108 is regulated according to the alcohol mixture ratio in fuel in use to gasoline, thereby ensuring the air-fuel ratio adapted to the type of fuel in use.