Using an update amount, an update amount calculating circuit manipulates a phase-control angle so as to perform feedback control such that a steering torque corresponds to a target torque. The steering torque is obtained by reducing a steering torque in magnitude by a predetermined value. The phase-control angle is used to convert a current command value to a value of a fixed coordinate system, for example. Using a guard value, a guard processing circuit performs a guard process on a current command value set by a command value setting circuit, so that the current command value becomes the current command value. The guard value is used to determine an appropriate range for a variation in the current command value in accordance with an amount by which the steering torque exceeds in magnitude the target torque.
