An electric power steering apparatus is provided, which has a first device for detection of steering torque, a motor, a motor drive unit, a second device for determining a target current based upon at least a signal of steering torque, a third device for detection of a motor current, and a control unit for generating a signal for motor drive based upon at least a deviation between the target current and motor current and transmitting the signal for motor drive to the motor drive unit. The apparatus has a feature that the control unit includes a fourth device for weakening a magnetic field within the motor according to the deviation or a value computed based upon the deviation.