To provide a fuel injection device immediately restarting an internal combustion engine even if a detected and stored stop crank angle reaches a low-accuracy value or an erroneous detection value.

When starting the engine, after starting angle momentum L1 is detected, that is, second fuel injection timing and the second amount of fuel injected are determined based on the starting angle momentum L1. Thereby, even if the stored stop crank angle is the erroneous detection value or the like, it becomes possible to optimize the fuel injection timing and the amount of fuel injected after the starting angle momentum L1 is detected and to immediately restart the engine.