As for the detention needle assembly body, while possessing ahead the sharp needle in the point, while being locked to the basic end of the needle and the inside needle, in order the needle hub and the inside needle outside is locked to the basic end of the outside needle and the outside needle of the air which passes in the basic end or the side section of the needle hub and the outside needle hub, to communicate with the lumen of the outside needle, while it is provided in opening and the outside needle hub which are provided, the possible hole or the slit is formed the inside needle, at the same time, passing, the seal component which the hole or the slit blocks the occasion where removal leaving it does the needleIt has possessed. With this detention needle assembly body, the inside of the hole or the slit and/or on the outside of the inside needle, the friction decrease processing which decreases the friction drag at those time is administered.留置針組立体は、先端に鋭利な針先を有する内針と、内針の基端部に固定された内針ハブと、内針が挿通される中空の外針と、外針の基端部に固定された外針ハブと、外針ハブの基端部または側方部に、外針の内腔と連通するように設けられた開口と、外針ハブに設けられ、内針を挿通可能な孔またはスリットが形成され、かつ、挿通された内針を抜去した際に孔またはスリットが閉塞するシール部材とを有している。この留置針組立体では、孔またはスリットの内面および/または内針の外面に、それらの間の摩擦抵抗を低減する摩擦低減処理が施されている。
