PROBLEM TO BE SOLVED: To provide a bubble generator capable of varying bubble diameters and condition of microbubbles in accordance with a users taste while a jetting flow containing the microbubbles is made to reach a further distant place.SOLUTION: A columnar cylinder 13 is arranged in the front position of a jetting nozzle 15 from which a jetting flow containing microbubbles is released into a bathing tub B. As the cylinder 13, both ends are made hemispherical and the cylinder 13 set in a such manner that its base end part is situated in the opening end face of a throttle releasing part 152 of the jetting nozzle. The cylinder 13 is given a dimension corresponding to a negative pressure region which is generated in a region near the axis X immediately after leaving the jetting nozzle of the jetting flow F. A threaded portion 130 of a prescribed length is formed in the outer periphery of the cylinder 13, and a threaded portion 165 of an inner peripheral face of an annular holding part 164 which is fixed to a supporting arm not shown in the figure, is externally fitted onto the threaded portion. When the cylinder 13 is rotated, adjustment is possible in the forward/backward position between positions K1, K2 across a reference position K.COPYRIGHT: (C)2012,JPO&INPIT【課題】 微細気泡を含んだ噴出流をより遠方まで到達させつつ、微細気泡の気泡径やその性状をユーザの好みに応じて変更し得る気泡発生装置を提供する。【解決手段】 微細気泡を含む噴出流が浴槽B内に放出される噴出ノズル15の正面位置に、円柱状の柱状体13を配設する。柱状体13として、両端部を半球状とし、柱状体13の基端部が噴出ノズルの絞り開放部152の開口端面に位置するように設定する。柱状体13を噴出流Fの噴出ノズルを出た直後から中心軸X近傍領域で生じる負圧領域に対応する大きさとする。柱状体13の外周に所定長さのネジ部130を形成し、図外の支持アームに固定された環状の保持部164の内周面のネジ部165を外嵌させる。柱状体13を回転させれば基準位置Kを挟んで位置K1,K2間を進退位置調整可能となる。【選択図】 図4