A control system for an internal combustion engine performs output control so that an engine output coincides with demand output by changing intake air flow rate or ignition timing of the engine. Output reduction control, wherein engine output is reduced, is performed when the demand output decreases. A retard limit output is calculated, and a retard limit intake air flow rate is calculated when the demand output is less than the retard limit output. The engine output is made to coincide with the demand output by retarding the ignition timing when the demand output is equal or greater than the retard limit output. When the demand output is less than the retard limit output, the ignition timing is retard to the limit and the intake air flow rate is controlled so as to coincide with the retard limit intake air flow rate.