A control device for a spark-ignition internal combustion engine that sets ignition timing based on a target value of a predetermined combustion-related parameter correlated with a combustion state and operates an ignition device in accordance with the ignition timing thus set. The control device calculates an actual value of the combustion-related parameter from an output value of the cylinder pressure sensor and feeds back the calculated value of the combustion-related parameter to the setting of ignition timing. Further, in parallel with the above processing, the control device calculates a value of a predetermined combustion variation parameter correlated with the magnitude of combustion variation from the output value of the cylinder pressure sensor. If the calculated value of the combustion variation parameter deviates from an allowable range of the combustion variation, the control device stops the feedback of the calculated value of the combustion-related parameter.