The syringe assembly 10 of the present invention comprises an outer cylinder 2 and a seal cap 3 mounted on the outer cylinder 2. The seal cap 3 includes a hollow portion 30 including a blocking distal end portion 31, an opening proximal end portion 32, a tubular tip portion housing portion 35 that houses the tubular tip portion 22, and a puncture needle housing portion 34, and a hollow portion 30 having the puncture needle A penetratable portion 33 into which the tip 61 can be inserted, and a projection 36 formed on the inner surface of the tube tip portion storage portion 35. The projecting portion 36 has a vertex portion 36 a and a distal side inclined portion 36 b extending toward the distal direction from the vertex portion 36 a. In the syringe assembly 10, the seal cap 3 is attached to the tube tip portion 22 of the outer tube 2, the puncture needle tip 61 penetrates into the insertable portion 33, and the projection portion 36 of the seal cap 3 and the tube tip portion 22 , And the distal end side inclined portion 36 b is pressed against the outer surface of the annular head portion 24 and is brought into close contact with the annular recess portion 25.本発明のシリンジ用組立体10は、外筒2と、外筒2に装着されたシールキャップ3とからなる。シールキャップ3は、閉塞先端部31と、開口基端部32と、筒先部22を収納する筒先部収納部35と穿刺針収納部34とを備える中空部30と、穿刺針6の穿刺用針先61が刺入可能な刺入可能部33と、筒先部収納部35の内面に形成された突出部36とを備える。突出部36は、頂点部36aと、頂点部36aより先端方向に向かって延びる先端側傾斜部36bとを有している。シリンジ用組立体10では、外筒2の筒先部22にシールキャップ3が装着され、穿刺用針先61が刺入可能部33内に刺入し、シールキャップ3の突出部36と筒先部22の環状凹部25とが係合し、かつ、先端側傾斜部36bが、環状頭部24の外面に押し付けられて密着した状態となっている。
