PROBLEM TO BE SOLVED: To provide an indwelling needle assembly of an improved structure that can accomplish prevention of the leakage of blood through an outer needle even when a long period of time has passed since manufacture.SOLUTION: A restraining ring 118 which is made movable relative to an elastic valve element 80 and located on an outer peripheral surface of the elastic valve element 80 to restrict the deformation of the elastic valve element 80 toward an outer peripheral side is provided on an outer needle hub 16. An engagement action unit 106 is provided which engages the restraining ring 118 located away from the elastic valve element 80 toward a tip end side and which moves the restraining ring 118 toward the elastic valve element 80 based on this engagement during removal of an inner needle hub 12 from the outer needle hub 16 so that the restraining ring 118 is located on the outer peripheral surface of the elastic valve element 80.COPYRIGHT: (C)2012,JPO&INPIT【課題】製造から長期間を経た場合にも、外針を通じての血液の漏出防止が実現され得る、改良された構造の留置針組立体を提供すること。【解決手段】弾性弁体80に対して相対移動可能とされて弾性弁体80の外周面上に位置することで弾性弁体80の外周側への変形を制限する拘束リング118が外針ハブ16に設けられている一方、弾性弁体80よりも先端側に外れて位置させられた拘束リング118に対して係合し、内針ハブ12を外針ハブ16から取り外すに際してかかる係合に基づいて拘束リング118を弾性弁体80側に移動させて弾性弁体80の外周面上に位置させる係止作用部106が設けられている。【選択図】図2
