Disclosed is a device for easily dissolving carbon dioxide in a bathtub, a footbath, or the like, and in particular, to provide a free carbonic acid supply device for a tub-in type bathtub that effectively enriches the free carbonic acid concentration. A nozzle for generating ultrafine bubbles, which has a substantially circular cylindrical shape and has a gas permeable material 16 constituting a bubble generating part formed of a craze film on a support body 2 having a bubble ejection hole 6. 8, the regulator 10, and the compression cylinder 12, the fastening cap 14 is fitted into the support 2, the carbon dioxide filled in the compression cylinder 12 is opened in the ultrafine bubble generating nozzle 8, and the bathtub The carbonic acid bath can be easily provided. [Selection] Figure 1【課題】浴槽及び足湯浴槽等に二酸化炭素を容易に溶け込ませる器具であり、特に遊離炭酸濃度を効果的に富加する浴槽投入式浴槽用遊離炭酸供給器を提供する。【解決手段】略円形の筒状であって、気泡噴出孔６を有する有低の支持体２に、気泡発生部を構成する気体透過材１６をクレーズフィルムにて形成する超微細気泡発生用ノズル８と、レギュレーター１０と、圧縮ボンベ１２を収容し、締結キャップ１４を支持体２に勘合して、圧縮ボンベ１２に充填されている二酸化炭素を超微細気泡発生用ノズル８内に開放し、浴槽に投入することにより、容易に炭酸浴が提供される。【選択図】図１
