Basically, the filling gas in a soap bubble dose not diffuse into the surrounding air, and the soap bubble can keep the filling gas concentration constant until its bursting. If the soap bubble is filled with an extinguishing gas, it can be used as a fire extinguishing ball. In order to clarify the extinguishment characteristics and mechanisms, we have performed blowout experiments of a methane-air jet diffusion flame by using the nitrogen-filled soap bubble and visualized the blowout processes by schlieren method. As a result, when the nitrogen-filled soap bubble contacts at the thermal boundary of the flame base of the jet diffusion flame, the soap liquid film ruptures and the extinguishing gas is supplied to the flame. Then the local extinction occurs at the flame base, and the rest flame lifts off. Finally, the whole flame is blown out.