In a carburetor and an exhaust gas recirculation system adapted to an internal combustion engine, the system comprises a first servomotor to be operated by pneumatic pressure and a first control valve actuated by the first servomotor to control the quantity of exhaust gases recirculated into an intake manifold from an exhaust pipe, and the carburetor comprises a second servomotor to be operated by pneumatic pressure and a second control valve actuated by the second servomotor to control the flow quantity of air to be mixed with fuel from a float chamber. The pneumatic pressure applied to the first and second servomotors is electrically controlled to satisfy the following function in relation to the engine intake manifold vacuum and the engine speed.Pe=f(Pv, N)where Pe is the pneumatic pressure applied to the servomotors, Pv and N respectively indicate the engine intake manifold vacuum and the engine speed.