A direct-injection spark-ignition engine including a governor for sensing the rotational speed of the engine, fuel injection pumps for injecting fuel at a rate which may be increased or decreased by a fuel control rack connected to the power shaft of the governor, fuel injection nozzles for directly injecting the fuel from the pumps into the respective engine cylinders, ignition plugs for igniting and burning the fuel charges injected from the nozzles by spark discharge, and suction air passages through which air flows toward the combustion chambers, characterized by throttle valves each of which is mounted within each suction air passage to open or close the same, and throttle control mechanisms each of which is connected to the throttle valve and the fuel control rack to open or close the valve in such a way that the valve opening is increased in proportion to an increase in the quantity of fuel injection.