Abstract: In an exhaust gas recirculation system including a recirculation passage to provide a communication between an intake pipe and an exhaust pipe of an internal combustion engine, a flow control valve associated with a pneumatic servomotor to control the quantity of exhaust gas flowing through the recirculation passage in accordance with the pneumatic pressure applied to the servomotor, and first and second electrically operated valves to selectively apply negative pressure and the atmospheric pressure to the servomotor, a digital computer is adapted to calculate a desired opening degree of the flow control valve in response to an electric signal indicative of operating conditions of the engine, to calculate each energization time of the valves defined by a difference between the actual opening degree of the flow control valve and the calculated value in response to an electric signal indicative of the actual opening degree of the flow control valve, and to generate an output signal indicative of the calculated