An inner needle having a sharp needle point to only the tip, the inner needle hub fixed to the proximal end of the inner needle and outer needle of a hollow inner needle is inserted, the manufacturing method of the indwelling needle assembly, the outer an outer needle hub fixed to the proximal end of the needle, provided on the outer needle hub, the inner needle is inserted therethrough, the sealing member made of an elastic material that exhibits a sealing function when the inner needle is removed A method and a door, producing an indwelling needle assembly is manufactured by assembling these, an insertion step of the insertion state is inserted from the side opposite to the needle point of the inner needle to the seal member, in the inserted state, a lubricant applying step of depositing a lubricant on the outer circumferential surface of the portion projecting from the seal member of the inner needle, by one reciprocate at least in the axial direction of the inner needle to the seal member, the sealing member the lubricant at least I and a reciprocating process to penetrate into the.留置針組立体の製造方法は、先端のみに鋭利な針先を有する内針と、内針の基端部に固定される内針ハブと、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る外針ハブと、外針ハブに設けられ、内針が挿通可能であり、内針が抜去された際にシール機能を発揮する弾性材料で構成されたシール部材とを備え、これらを組み立てて製造される留置針組立体を製造する方法であって、シール部材に内針を針先と反対側から挿通して挿通状態とする挿通工程と、挿通状態で、少なくとも内針のシール部材から突出した部分の外周面に潤滑剤を付着させる潤滑剤付与工程と、シール部材に対して内針をその軸方向に少なくとも1回往復動させて、潤滑剤をシール部材の内部に浸透させる往復動工程とを有する。
