An engine system may include an engine having an intake line flowing an intake gas supplied to the combustion chambers; an intake manifold; a throttle valve provided at a front of the intake manifold and controlling an air amount supplied to the combustion chamber; an electric supercharger provided at the throttle valve and including a motor and an electric compressor operated by the motor to supply the supercharged air to the combustion chamber; an exhaust gas processing device purifying an exhaust gas generated in the combustion chamber; and an exhaust gas recirculation device including a recirculation line branched from the downstream portion of the exhaust gas processing device and joined to the intake line of the upstream portion of the electric compressor, an EGR cooler mounted at the recirculation line, and an EGR valve mounted at a part where the recirculation line and the intake line are joined.