A waveform detector detects a variation in fuel pressure based on a detection value of a fuel pressure sensor as a fuel pressure waveform. A determining portion determines whether an interval between injections is zero or smaller than a predetermined value based on the detected fuel pressure waveform when multi-step-injection is performed. A correcting portion corrects an injection command signal indicative of an injection start timing and an injection end timing corresponding to a target injection state in a manner that the interval is increased when the interval is determined to be zero or smaller than the predetermined value.