Needle assembly body 1 is formed the hub 4 which keeps kanura 3 and advance and retreat moving, the protective unit from the tubular section 6 where surrounds the outer circle of 5 which surrounds the point of above-mentioned kanura 3 and the above-mentioned protective unit 5, protective unit 5, from the above-mentioned tubular section 6 in the wire protector 7 which is appeared frequently butt 8 has the constitution which formed in series just, the above-mentioned hub connects with 4 and tubular section 6 and forms the hub body. In addition, before the using where in the above-mentioned wire protector 7 guide expedient G can provide engagement projection 24, in the hub body, wire protector 7, is categorized to advance position state (the figure 4 (a))When the empty it backs up, engagement projection 24 this touching to tilt slope 14a, while turning, to move to the rear, (the figure 4 (b))The busy condition where wire protector 7 is categorized to retreat position (the figure 4 (c))When the empty it advances, engagement projection 24 moving to the front, after the using it is locked by retention section B, retreat is obstructed. It is low, being production possible in cost, in addition it can use safely.針組立体1は、カヌラ3を保持するハブ4と、進退動して上記カヌラ3の先端を囲繞する保護ユニット5と、上記保護ユニット5の外周を囲繞する筒状部6とから構成され、保護ユニット5は、上記筒状部6より出没する保護カバー7にばね部8を直列に一体成形した構成を有し、上記ハブ4と筒状部6とは連結してハブ体を構成している。また、上記保護カバー7には係合突起24を、ハブ体にはガイド手段Gが設けられ、保護カバー7を、前進位置に位置する使用前状態(図4(a))から後退させると、係合突起24が傾斜面14aに当接して回転しながら後方に移動し(図4(b))、保護カバー7が後退位置に位置する使用状態(図4(c))から前進すると、係合突起24が前方に移動して使用後保持部Bに固定され、後退が阻止される。低コストに製造可能で、また安全に使用することができる。
