The needle tube which possesses ahead the sharp needle in the point (5) and 1st the needle tube (5) at least covers ahead the needle the tip of position and the needle to expose the stab needle assembly body (1), 1st with 2nd position of basic edge side than position movement possibly the protector which is supported vis-a-vis the needle tube (5) (7) with, the protector (7) the energization expedient which energization is done (11) with to have for the direction which faces to 1st position from 2nd position the needle tube (5) according to axial direction, the protector (7), tube shapeIt is something which it forms, inside that, the advanced large diameter section (74) with, the advanced large diameter section (74) it is provided continually on basic edge side, the advanced large diameter section (74) from the small diameter section of small diameter (75) with is formed, the protector (7), 1st the occasion where it inclines vis-a-vis the needle tube (5), the needle tube (5) the part of basic edge side than ahead the needle of the peripheral section the small diameter section (75) this touches with part at position.穿刺針組立体(1)は、先端に鋭利な針先を有する針管(5)と、針管(5)の少なくとも針先を覆う第1の位置と、針先が露出し、第1の位置よりも基端側の第2の位置との間を針管(5)の軸方向に沿って移動可能に針管(5)に対し支持されたプロテクタ(7)と、プロテクタ(7)を第2の位置から第1の位置に向かう方向に付勢する付勢手段(11)とを備え、プロテクタ(7)は、筒状をなすものであり、その内部には、先端大径部(74)と、先端大径部(74)の基端側に連続的に設けられ、先端大径部(74)より小径の小径部(75)とが形成され、プロテクタ(7)が、第1の位置で針管(5)に対して傾斜した際に、針管(5)の外周部の針先よりも基端側の部分が小径部(75)の一部と当接する。
