[PROBLEMS] To connect a milking device having two different connection calibers and stably hold the milk collected in a single milking milk collected in a breast milk storage bag with the breast milk storage bag. Providing adapters for use in breast pumps. A main body portion and a first connection portion having a first caliber, and a first connection portion provided at a first end of the main body portion and connected to either a breast pump or a breast milk storage bag. A second connection portion 12 having a second diameter larger than the first diameter, a second connection portion provided at the second end of the main body portion and connected to the other of the breast pump and the breast milk storage bag, and an outer surface of the main body portion An adapter 10 comprising: a first holding structure 13 that is positioned and prevents the clip 30 that fixes the breast milk storage bag to the adapter from sliding in the longitudinal direction of the main body from the first end of the main body. [Selection] Figure 1【課題】２種類の異なる接続口径の搾乳器と連結することができるとともに、母乳保存袋に収集した通常１回の搾乳で搾乳された母乳を、母乳保存袋との連結を安定して保持できる搾乳器に用いるアダプター等を提供すること。【解決手段】本体部１４と、第１口径を有する第１接続部１１で、本体部の第１端に設けられ搾乳器及び母乳保存袋５０のいずれかに連結される第１接続部と、第１口径よりも大きい第２口径を有する第２接続部１２で、本体部の第２端に設けられ搾乳器及び母乳保存袋の他方に連結される第２接続部と、本体部の外面に位置し、母乳保存袋をアダプターに固定するクリップ３０が、本体部の第１端から本体部の長手方向に滑脱することを防止する第１保持構造１３とを備えるアダプター１０。【選択図】図１
