PURPOSE: To provide a fuel injection device by which right corrective fuel injection is carried out by means of detected pressure even at the time of high rotational speed of an engine, in an air assisting type fuel injection device for detecting pressure directly downstream from a fuel injection port of a fuel injection valve, and performing fuel correction.

CONSTITUTION: A fuel injection valve 8, an air assisting passage 12, a pressure sensor 19 and an ECU 9 are provided in the present fuel injection device, and basic fuel injection quantity TAUbase is corrected by the ECU 9, based on pressure P1 detected by a pressure sensor and correction of a fuel injection quantity guaranteed by the calculated correction quantity is applied to the next fuel injection taking place just after detecting the pressure, and thereby its calculation time is secured.