Exhaust purification device for gasoline engine

An exhaust purification device for a spark ignition engine, the apparatus comprising: a three-way catalyst for the removal of pollutants in exhaust gases, wherein the three-way catalyst disposed in an exhaust passage of the gasoline engine; and a control unit for temporarily transferring the gas flowing into the three-way catalyst exhaust gases in excess of oxygen when the air flowing into the three-way catalyst exhaust gas are converted into a stoichiometric or rich gas mixture, and the stoichiometric or rich gas mixture is maintained continuously at least for a predetermined reference time period.