A turbocharged engine control system having exhaust gas recirculation control means (26) which detects a value relating to an actual excess air ratio and feedback controls an exhaust gas recirculation valve (5) so as to bring the actual excess air ratio into coincidence with a target excess air ratio and turbine efficiency control means (28) which controls a turbocharger (8) to change turbine efficiency of the turbocharger is comprised of detection means (12) for detecting a value relating to a pressure difference between pressure before and after the exhaust gas recirculation valve (5) and control means (26) for controlling the turbine efficiency control means (28) to vary a change rate at which the turbine efficiency changes so as to become lower as the pressure difference rises. With the turbocharged engine control system, the control is properly performed to improve fuel economy and reduce particulate such as smoke and unburnt fuel and NOx emissions in exhaust gases without causing overshooting and/or hunting.