PURPOSE: To make it possible to mix different fluids to each other with good efficiency, by providing a vibration plate in a cylinder in a cantilevered support state and violently impinging different fluids to be mixed to the bracket provided to the leading end of the vibration plate to apply ultrasonic vibration to said vibration plate.

CONSTITUTION: First and second heads 3, 4 are connected through a cylinder 2 having a discharge port 11 and the oil supply port 5 communicated with the cylinder 2 is formed to the first head 3 on the axis of the cylinder 2. The water supply port 7 communicated with the cylinder 2 is formed to the circumference of the oil supply port 5 and a vibration plate 9, which is fixed to the side of the second head 4 at one end thereof and has a bracket 10 fixed to the free end side thereof at the position opposed to the oil supply port 5 and the water supply port 7, is arranged in the cylinder 2. That is, different fluids to be mixed are violently impinged to the bracket 10 to apply ultrasonic vibration to the vibration plate 9 and can be uniformly mixed to each other by this ultrasonic vibration with good efficiency.