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.