To prevent deterioration of exhaust emission by preventing a change of cylinder inside intake fuel quantity due to a change of valve overlapping quantity.

This fuel injection control device of an internal combustion engine is constituted to correct fuel injection quantity of a fuel injection valve 20 in accordance with variation of an attached fuel correction coefficient by computing the attached fuel correction coefficient in correspondence with attached fuel quantity to attach on an air intake port 19a, etc. (a change of evaporation of attached fuel quantity due to a change of valve overlapping quantity, that is, information to evaluate a change of the cylinder inside intake fuel quantity) in accordance with air intake valve timing. Consequently, it is possible to prevent a change of an air-fuel ratio due to the change of the valve overlapping quantity and to prevent deterioration of the exhaust emission by correcting the fuel injection quantity so as to compensate the change of the cylinder inside intake fuel quantity due to the change of the valve overlapping quantity (a change of evaporation of the attached fuel quantity). Additionally, this device is devised to prohibit fuel injection quantity correction in accordance with air intake valve timing in sudden acceleration, in heavy fuel judgement and in abnormality judgement of a variable air intake valve timing device 32.