There is provided an electric power steering system that makes it possible to reduce an uncomfortable feeling given to a driver even when a detected steering torque value is held. The controller computes a detected steering torque value based on the detection signal, and provides compensation based on a compensation value to a basic current command value to compute a current command value. The controller executes feedback control for causing a current value of the motor to follow the current command value. The controller executes normal control in which the detected steering torque value is periodically updated and backup control in which periodic updating of the detected steering torque value and holding of the detected steering torque value are alternately executed. The controller switches compensation value between a compensation value used during execution of the normal control and a compensation value used during execution of the backup control.
