Fuel injection control device

A fuel injection control device applied to a fuel injection system including a pressure sensor that detects a pressure of fuel supplied to a fuel injection valve, the device comprising:

• a reference interval calculation section configured to calculate a reference interval between an end time of a decrease interval where the pressure decreases as a fuel injection rate increases and a start time of an increase interval where the pressure increases as the fuel injection rate decreases on a pressure waveform detected by the pressure sensor;
• an integration interval setting section configured to set, in the reference interval, an integration interval where an influence of a disturbance on the fuel pressure decrease due to a target injection is suppressible;
• and
• a decrease amount calculation section configured to calculate a corresponding pressure decrease amount, which is an amount of the fuel pressure decrease corresponding to a maximum injection rate of fuel of the target injection, based on an integral value obtained by integrating the amount of the fuel pressure decrease due to the target injection in the integration interval.