A control system for controlling an internal combustion engine which discharge exhaust gases through an emission purifier includes a controller which increases the quantity of intake air drawn into the internal combustion engine while the internal combustion engine is idling after the internal combustion engine has started to operate, to a level which is greater by a predetermined increase than the quantity of intake air drawn into the internal combustion engine while the internal combustion engine is idling normally. The controller also generates a command value for ignition timing of the internal combustion engine according to a feedback control process to converge the rotational speed of the internal combustion engine toward a predetermined target rotational speed, and controlling the ignition timing of the internal combustion engine based on the generated command value thereby to retard the ignition timing. The controller establishes the target rotational speed by changing the target rotational speed from a preset rotational speed toward a predetermined idling speed after the rotational speed of the internal combustion engine has reached the preset rotational speed which is higher than the idling speed after the quantity of intake air drawn into the internal combustion engine has started being increased.