To optimize the promotion of atomization of fuel by dispersion gas in a full-load range regardless of the level of engine load, in a fuel injection device 1 provided with an air blast valve 2.

A flow passage is constituted so that both EGR gas and air discharged from an air pump 39 can be used as dispersion gas, and a control system is provided so that the mixing ratio of the EGR gas in the dispersion gas to air supplied from an air supply path 40 can be controlled. Namely, when the engine load is low, only the EGR gas is supplied to the air blast valve 2 as the dispersion gas, when the engine load is high, only the air discharged from the air pump 39 is supplied to the air blast valve 2 as the dispersion gas, and when the engine load is middle, the mixing ratio is controlled according to a returnable amount of EGR gas or the like, whereby the atomization promoting effect by the EGR gas can be maximized.