At least after off of an injection pulse of partial lift injection, a difference between a first filtered voltage being a negative terminal voltage of a fuel injection valve filtered by a first low-pass filter and a second filtered voltage being the terminal voltage filtered by a second low-pass filter is calculated, and time from a predetermined reference timing to a timing when the difference between the filtered voltages has an inflection point is calculated as voltage inflection time. Subsequently, an injection quantity corresponding to current voltage inflection time is estimated for each of injection pulse widths with a relationship between the voltage inflection time and the injection quantity, the relationship being beforehand stored for each of the injection pulse widths. A map defining the relationship between the injection pulse width and the injection quantity is created based on a result of such estimation, and a required injection pulse width corresponding to a required injection quantity is calculated using the map.