An object of the present invention is to provide a nipple in which the amount of deformation of the nipple is suppressed as much as possible so that twitching or the like does not occur. A nipple to be mounted on a baby bottle, comprising a baby bottle body and a cap screwed into an opening of the baby bottle, wherein the nipple is fitted with the nipple body and the cap. And a flange for mounting the nipple between the opening of the baby bottle and the cap, wherein the flange is formed in at least two stages of a thick portion and a thin portion, The part is sandwiched between the opening of the baby bottle and the cap. An annular groove was provided on the upper surface of the thin portion of the flange portion. [Selection diagram] FIG.【課題】乳首の変形量を極力抑えて引き攣れなどが生じることがない乳首を提供する。【解決手段】哺乳瓶本体と、この哺乳瓶の開口に対して螺合するキャップとからなる哺乳瓶に装着する乳首であって、この乳首は、乳首本体と、この乳首を前記キャップに嵌め込むための凹溝と、この乳首を前記哺乳瓶の開口と前記キャップの間に装着するためのフランジ部とからなり、このフランジ部は厚肉部と薄肉部の少なくとも二段に構成し、前記薄肉部を前記哺乳瓶の開口と前記キャップの間で挟み込む。フランジ部の薄肉部には、上面に環状溝を設けた。【選択図】図２
