Fuel injection control system for internal combustion engine and control method therefor

A fuel injection control system for an internal combustion engine, which is capable of properly calculating a correction amount according to a fuel injection pressure, thereby enabling accurate control of a fuel injection amount. The system executes a minute amount injection that injects a predetermined minute amount of fuel from a fuel injection valve during a fuel cut operation that interrupts fuel injection for obtaining output of the engine, detects a change in engine rotation during the execution of the minute amount injection, detects a pressure of fuel injected from the fuel injection valve as the fuel injection pressure, calculates the correction amount for correcting a control input for controlling the fuel injection amount injected from the fuel injection valve using the detected change in engine rotation and the detected fuel injection pressure, and corrects the control input according to the calculated correction amount.