To provide a control device of an accumulator fuel injection device capable of determining the static leak amount of a fuel injection valve at high frequency and with accuracy, and increasing the accuracies of various control that utilizes fuel leak amounts.

The control device for an accumulator fuel injection device is capable of feedback control of the pressure of a common rail by control of a flow control valve based on a deviation between the desired pressure of the common rail and actual pressure, and includes a fuel non-injection state detection means for detecting a fuel non-injection state in which fuel injection quantity is zero during operation of the internal combustion engine, a desired pressure changing means for changing the desired pressure to a predetermined learning value while the fuel non-injection state is detected, and a static leak amount learning means for learning a static leak amount based on a control parameter of the flow control valve under a state in which a deviation between desired pressure and the actual pressure is within a predetermined range and under a state in which actual pressure is stable, after the desired pressure has been changed to the learning value.