PROBLEM TO BE SOLVED: To provide a breast pump where breast milk never goes around to a negative pressure forming means and which is effectively prevented from being broken or becoming insanitary.SOLUTION: The breast pump is provided with: a breast pump main body 21 comprising a milking part 22 to be abutted on one of the mammas of a user and an inner pressure changing means 41 connected to the milking part. The breast pump has a pressure transmission part 30 for transmitting pressure by separating a sealed space formed in milking and the pressure changing means watertight from each other. The pressure transmission part has a deforming part 51 where a volume in the sealed space is changed by the movement of the pressure changing means. The deforming part 51 has: an opening whose one end side is opened in a case 31 a bottom part 52 the other end side of which is closed and a wall part 53. A fragile part 54 is formed at the wall part, and a wall surface part is deformed so that the opening M4 and the bottom part of the deforming part can approach and can be separated according to the variation of pressure by the pressure changing means.COPYRIGHT: (C)2006,JPO&NCIPI【課題】負圧形成手段に母乳が回り込むおそれがなく、破損や非衛生な状態となることを有効に防止することができる搾乳器を提供すること。【解決手段】使用者の乳房に当接される搾乳部22を含む搾乳器本体21と、前記搾乳部と接続された内圧変更手段41とを備え、搾乳に際して、形成される密閉空間と、前記圧力変更手段とを液密的に分離して、圧力を伝達する圧力伝達部30を有し、前記圧力伝達部が、前記密閉空間内における体積が、前記圧力変更手段の動きにより変化する変形部51を有し、この変形部51は、ケース31内で一端側が開放された開口と、他端側が閉止された底部52と、壁部53とを有し、この壁部に脆弱部54が形成され、前記圧力変更手段による圧力の変動に応じて、前記変形部の前記開口M4と前記底部とが近接・離間するように前記壁面部を変形させる搾乳器。【選択図】 図1
