PROBLEM TO BE SOLVED: To provide a ventilation adjustment structure for eliminating negative pressure upon feeding milk and preventing the leak of milk.SOLUTION: In a feeding bottle including a nipple 2 made of an elastic material, a feeding bottle body 1, and a cap 3 mounting the nipple 2 to hold between an opening part of the feeding bottle body 1 and itself, a ventilation adjustment structure is obtained in such a manner that a flange part 24 that can be placed on a top surface of the opening part of the feeding bottle body 1 and has a diameter slightly larger than the maximum diameter of the top surface is formed at the lower end part of the nipple 2, a V shape groove 24a is arranged by depression in a ring shape over a whole circumference on the upper surface of the flange part 24, a flat open part 24b continuing from the bottom of the V shape groove 24a is formed in an external direction of a part of the groove, a ventilation groove 24c is arranged by depression in a diameter direction on a lower surface of the flange part 24 corresponding to the open part 24b, and the other hand, a ring shape projected line rib 32a fittable into the V shape groove 24a is provided on a lower surface of an inward flange 32 arranged in the cap 3.COPYRIGHT: (C)2014,JPO&INPIT【課題】授乳時の負圧の解消と、ミルクの漏れを防止した通気調節構造を提供する。【解決手段】弾性素材の乳首2と、哺乳びん本体1と、乳首2を装着して哺乳びん本体1の開口部との間に挟持するキャップ3からなる哺乳びんにおいて、乳首2の下端部分に哺乳びん本体1の開口部の天面に載置可能でその最大径より僅かに大きい径のフランジ部24を形成し、このフランジ部24の上面全周にわたって環状にV字溝24aを凹設すると共に、その一部の外側方向に前記V字溝24aの底部と連続して平坦な開放部24bを形成し、その開放部24bに対応するフランジ部24の下面には通気溝24cを直径方向に凹設する一方、キャップ3に設ける内向きフランジ32の下面に、V字溝24aに嵌入可能なリング状の突条リブを32a設けて通気調節構造とした。【選択図】図5