DIFFUSION DEVICE

PROBLEM TO BE SOLVED: To miniaturize the device by rotating an impeller in the prescribed direction with an underwater revolving driving machine to generate a vortex, making the gas fed through a gas feed pipe to eject by negative pressure caused in the liquid at the back side in the rotational direction of the impeller, and allowing the gas to intrude in the vortex. SOLUTION: When the underwater revolving driving machine 2 is operated in liquid A, the impeller 3 is rotated and the vortex is generated and negative pressure is generated in the liquid A at the back side in the rotational direction of the impeller of the blade 12. The gas B fed from the gas feed device is ejected through a straight pipe 20 of a gas feed pipe 7, an L shaped pipe 19, a through hole 18, and an inner hole 14 of a gas ejection path 4 through an ejection port 15, and is intruded in the liquid A in negative pressure. At this time, the liquid A at the lower side of a straightening plate 5 is introduced into the impeller 3 through a sucking hole 6, and also the liquid A contained gas B is guided to the side direction with the straightening plate 5. Since the main parts of such a diffusion device 1 is constituted by the underwater revolving driving machine 2, the impeller 3, and the straightening plate 5, the device can be miniaturized.