A characteristics-detecting-portion analyzes a fuel injection condition based on a fuel pressure waveform which represents a variation in a detection value of the fuel pressure sensor and then detects the fuel-injection-characteristic value based on the analyzed fuel injection condition. The detected parameter is learned and stored in a memory in association with a fuel temperature detected by a fuel temperature sensor. A fuel-injection-rate model is established based on the learned detected parameters. A command-fuel-injection start time and a command-fuel-injection period are defined by use of the fuel-injection-rate model and the current fuel temperature.