A steering actor of an independent type steer-by-wire system comprises a
housing fixed to a vehicle body and an ultrasonic motor. The ultrasonic
motor has a stator internally fixed to the housing and a rotator rotating
relative to the stator when an electric current is applied. A steering
rod having a first end and a second end penetrates through a center
portion of the ultrasonic motor. The first end of the steering rod
extends out of the housing for connection to a tie rod. A movement
conversion means is operably associated with the steering rod for
converting rotating movement of the ultrasonic motor into linear movement
of the steering rod.