When the disclosed electric power steering apparatus designed for use in a right/left-hand-drive vehicle is installed on a left/right-hand-drive vehicle, methods of (1) mirror-reversing the apparatus except for the rotation angle sensor; arranging the sensor in a consistent direction relative to the rack/column shaft; and counterchanging V and W phases of the motor, or (2) mirror-reversing the apparatus except for the rotation angle sensor; arranging the sensor in a consistent direction relative to the rack/column shaft with +120.degree. (or +240.degree.) offset relative to the motor; and counterchanging U and V (or U and W) phases of the motor, are performed.