An engine system includes an intake line, an exhaust line, an exhaust gas recirculation (EGR) system, a turbocharger including a turbine provided in the exhaust line, and a compressor provided in the intake line, wherein the compressor compresses outside air, an intake bypass line which branches off from the intake line at a rear end of the compressor and merges into the intake line at the front end of the compressor, a recirculation valve installed at a point at which the intake bypass line and the intake line merge together, and a controller which controls operations of opening and closing the recirculation valve so that a portion of the intake gas compressed by the compressor is supplied into the intake line at the front end of the compressor through the intake bypass line, or the intake gas is supplied into the combustion chamber through the intake bypass line.