To provide an acting device such as a fountain of which the surface of fountain itself becomes wonderfully beautiful and is high in aesthetic appreciation.

This acting device is provided with a falling surface which is composed of a stored liquid surface and a basic board, etc., a spread controlling surface which is disposed above the falling surface and a rectifying means which allows the liquid rectified toward the spread controlling surface to fall or ascend. Therein, by means of the rectifying means, the rectified liquid is guided to the spread controlled surface from above or from below, thereby, the liquid is spread downward and the fountain surface of a flared shape, etc., is formed in such a manner that a closed inner space exists above the falling surface. In addition, this acting device is provided with a means which expands the fountain by introducing gas into the inner space.