A fuel injection device for internal combustion engine capable of providing an appropriate fuel injection performance in the entire operating range of an engine, further reducing the amount of nitrogen oxides (NOx), and increasing a mechanical reliability, comprising a fuel injection pump having a plunger part and a fuel path having a main solenoid valve provided therein, a fuel feed part for feeding fuel to the fuel injection pump, a fuel injection pipe for feeding fuel from the fuel injection pump to the injection nozzle part, and a sub solenoid valve provided in an overflow pipe for returning the fuel leaked from the fuel injection pump to the fuel feed part, characterized in that an orifice is provided in the fuel path and the overflow pipe.