Abstract: A foaming nozzle is connected to a gas generating device for generating a high-pressure gas which has a pressure higher than an atmospheric pressure and spouting the high-pressure gas from the tip of the nozzle, and the foaming nozzle foams, while stirring, a liquid located in the direction of the spouting. The foaming nozzle has formed in the tip thereof at least two kinds of spouting holes for spouting the high-pressure gas. At least one kind of spouting hole is formed in a shape different from the shape of the other kind of spouting hole so as to spout the high-pressure gas at a speed different from the speed of the high-pressure gas spouted from the other kind of spouting hole.