PURPOSE: To provide an ultrasonic defoaming device equipped with a foam detector by which foam is surely detected in a contaminated atmosphere of a limited space irrespective of kinds of chemicals by making an ultrasonic vibrator for transmitting ultrasonic waves for breaking foam on the surface of the liquid also serve as an ultrasonic receiver for receiving reflected waves from the surface of the liquid and the foam.

CONSTITUTION: In an ultrasonic defoaming device equipped with an ultrasonic vibrator 48 for transmitting ultrasonic waves for breaking foam on the surface of the liquid, the ultrasonic vibrator 48 is used also as an ultrasonic receiver for receiving reflected waves from the surface of the liquid or the foam. When the existence of foam swelling on the surface of the liquid is detected by the reflected waves received by the ultrasonic vibrator 18, intense ultrasonic waves are transmitted from the ultrasonic vibrator 48 to break the foam. Further, after the defoaming by the ultrasonic vibrator 48 is performed in a prescribed time, the reflected waves are received by the ultrasonic vibrator 48. As a result, the ultrasonic defoaming device equipped with a foam detector by which foam is surely detected in a contaminated atmosphere of a limited space irrespective of kinds of chemicals is provided.