Problem to be solved: to provide a retractable needle assembly capable of completely discharging the blood staying in the outer needle base in a short time.Solution: a storage needle assembly 1 is provided with an outer needle 2, an outer needle base 3, a hollow cylindrical member 4, a slit 45 capable of opening and closing, and a stopper valve 44 fitted into the hollow cylindrical member 4, and a connecting member to which the base end portion is inserted into the slit 45 of the hemostatic valve 44 when the hollow cylindrical member 4 is pushed in the tip direction 5.The outer needle base 3 has a small diameter portion 34 and a large diameter portion 33 extending from the small-diameter portion 34 to the distal end side.The hollow cylindrical member 4 is provided with a first notch 41 on the proximal end side and having a vent groove 43 for connecting the tip 42 and the first notch 41 to the outer peripheral surface, and can be advanced to the tip position from the base end position, and the second notch 54 of the projection 53 of the connection member 5 is opened in the direction different from the first notch 41 .Diagram【課題】外針基内に滞留する血液を短時間で完全に排出できる留置針組立体を提供する。【解決手段】留置針組立体１は、外針２と、外針基３と、中空円筒部材４と、開閉自在のスリット４５を備え中空円筒部材４に内嵌される止血弁４４と、中空円筒部材４が先端方向に押動されたときに基端部が止血弁４４のスリット４５に挿入される接続部材５とを備える。外針基３は小径部３４と、小径部３４より先端側に延在する大径部３３とを備える。中空円筒部材４は基端側に第１の切欠部４１を備え、外周面に先端部４２と第１の切欠部４１とを接続する通気溝部４３を備え、基端位置から先端位置へと前進可能であり、接続部材５の突起部５３の第２の切欠部５４は第１の切欠部４１と異なる方向に開口している。【選択図】 図１
