The present invention provides an engine system. The engine system may include: an engine including cylinders that generate a driving torque by combusting fuel; a first intake manifold connected to anintake line through which flows intake air into some of the plurality of cylinders; a second intake manifold supplying the intake air to the other cylinders of the plurality of cylinders through thefirst intake manifold; a first exhaust manifold connected to some cylinders that are connected to the first intake manifold; a second exhaust manifold connected to some other cylinders that are connected to the second intake manifold; a recirculation line branched from the second exhaust manifold to be coupled to the second intake manifold; a recirculation inlet valve disposed at a point at whichthe recirculation line and the second exhaust manifold are joined; and a manifold connection valve disposed on an intake line between the first intake manifold and the second intake manifold.