PROBLEM TO BE SOLVED: To provide a prefilled syringe in which rotation is not necessary in attaching a plunger to a gasket, and in which a rotational force can hardly be transmitted to the gasket even if the attached plunger is rotated.SOLUTION: The gasket 3 of the prefilled syringe 1 includes a gasket body 6 and a plunger attaching member 7. The gasket body 6 includes an anti-loosening rib 62 for the plunger attaching member disposed on the inner surface. The plunger attaching member includes: an outer surface projection 73 to be engaged with the annular rib 62 of the gasket body 6 a plurality of elastically deformable inner projections 75a extending toward the center of the plunger attaching member 7 from the inner surface and deformation controlling projections 76a extending toward the rear ends from the rear end faces of the respective inner projections. The plunger 4 includes a distal end 42 which can penetrate into the plunger attaching member 7, and an outer surface projection 43 to be engaged with a plunger anti-loosening locking part of the plunger attaching member 7.COPYRIGHT: (C)2012,JPO&INPIT【課題】ガスケットへのプランジャ装着時に回転の必要がなく、装着後のプランジャを回転させてもガスケットに回転力が伝達されにくいプレフィルドシリンジを提供する。【解決手段】プレフィルドシリンジ1のガスケット3は、ガスケット本体6とプランジャ装着用部材7とからなり、ガスケット本体6は、内面に設けられたプランジャ装着用部材抜け止め用リブ62を備え、プランジャ装着用部材は、ガスケット本体6の環状リブ62と係合する外面突出部73と、内面よりプランジャ装着用部材7の中心方向に延び弾性変形可能な複数の内部突出部75aと、各内部突出部の後端面より後端方向に延びる変形規制用突出部76aとを備える。プランジャ4は、プランジャ装着用部材7内に侵入可能な先端部42と、プランジャ装着用部材7のプランジャ抜止用係止部と係合する外面突起部43とを備える。【選択図】図17
