An exhaust gas purification device for an internal combustion engine

An NOx occluding and reducing catalyst is disposed in an exhaust gas passage of an internal combustion engine that operates at a lean air-fuel ratio. When the engine is operating at a lean air-fuel ratio, the NOx occluding and reducing catalyst absorbs NOx in the exhaust gas. To release NOx, the engine is operated at a rich air-fuel ratio so that the exhaust gas flowing into the NOx occluding and reducing catalyst acquires a rich air-fuel ratio.