FUEL INJECTION DEVICE FOR INTERNAL COMBUSTION ENGINE

Even when only fuel oil is injected into a cylinder liner, decrease in fuel injection pressure, deterioration in combustibility, and degradation in performance of an internal combustion engine are prevented, while increase in dust and black smoke is also prevented. In a fuel injection device (1) for an internal combustion engine, capable of selectively injecting, from a fuel injection valve (3), a mixture of fuel oil and an inert substance in a multilayered state or in an emulsion state, or fuel oil only, a cam (10) for lifting up a plunger (7) of a fuel injection pump (2) that pressurizes and feeds the mixture of fuel oil and the inert substance in a multilayered state or in an emulsion state, or the fuel oil to the fuel injection valve (3) includes: a first cam for use in lifting up the mixture of fuel oil and the inert substance in a multilayered state or in an emulsion state; and a second cam for use in lifting up the fuel oil only.