When a vehicle is quickly steered while the vehicle is travelling at an extremely low speed, a load on an in-vehicle power supply is reduced without deteriorating a steering feeling by reducing a motor driving current. A steering speed is compared with a threshold. When the steering speed is lower than the threshold, the process proceeds to step S6. In step S6, a voltage value of a battery power supply, which is used as a prescribed value, is set as a limit voltage in order to reduce a motor consumption current. When the steering speed is higher than the threshold, a value “V0/n” lower than the prescribed value is set as the limit voltage to reduce a consumption current when the steering wheel is steered without driving. “n” is “delay adjustment parameter”, and is a real number that exceeds 1.