In an engine system, an ignition timing is changed in accordance with operation parameters of an engine. The engine system includes an exhaust gas clarifying equipment with a catalyst to clarify the specified components in the exhaust gas, catalyst temperature detecting unit for estimating or detecting the temperature of the catalyst, torque fluctuation detecting unit for detecting the state of fluctuation of an output torque of the engine, and ignition timing calculating unit for calculating the final ignition timing on the basis of the detected results of the torque fluctuation detecting unit and the catalyst temperature detecting unit.