Provided is an ultrasonic actuator on which tuning that has little effect on vibration characteristics of a vibrator is performed. The ultrasonic actuator includes an ultrasonic vibrator (12), a housing (16) that rotates with vibration of the ultrasonic vibrator, and pantograph preload mechanisms (150, 151) that hold the ultrasonic vibrator at a node of vibration of the ultrasonic vibrator and generate pressure with which the ultrasonic vibrator is pressed against the housing.
