An internal combustion engine system includes: an internal combustion engine; a valve regulating exhaust gas flow rate to an intake system; an exhaust gas recirculation system opening the valve to recirculate the exhaust gas to the intake system; an intake air flow rate detecting device detecting air flow rate introduced into the engine; and a controller, when fuel injection is stopped, controlling the engine to start the fuel injection at a rate obtained by adding a first flow rate to a reference flow rate for a stoichiometric air-fuel ratio based on the detected air flow rate when the valve opening degree is lower than a predetermined degree, and controlling the engine to start the fuel injection at a rate obtained by adding a second flow rate, larger than the first flow rate, to the reference flow rate when the valve opening degree is no less than the predetermined degree.