An ultrasonic actuator (2) includes an actuator body (3) generating a driving force, a case (4) containing the actuator body (3), and support rubbers (51) placed between the actuator body (3) and the case (4) to elastically support the actuator body (3) at both sides of the actuator body in a supporting direction. The case (4) includes a first case (8) having an opening at a position where one of the support members (51) is placed and a second case (9) coupled to the first case (8) to cover the opening in the first case (8). The support rubbers (51) are compressed as the second case (9) is coupled to the first case (8) and elastically support the actuator body (3) in the compressed state.