PROBLEM TO BE SOLVED: To provide a plunger rod and syringe for stopping loosening between the male screw thread of the plunger rod and the female screw thread of a gasket and also suppressing the deformation of the seal part in the gasket.SOLUTION: The plunger rod includes projection parts 34 arranged between a plurality of juxtaposed screw thread pieces 311a, 311a and projecting from the outer peripheral part of a base body 33. The projection parts 34 include engagement parts 341 positioned in the thread grooves 312 of the male screw thread 31 so as to be engaged with the thread ridges 211 of the female screw thread 21, and also are arranged to be separate from the respective screw thread pieces 311a, so as to allow the thread ridges 211 of the female screw thread 21, which are resiliently deformed by the engagement with the engagement parts 341, to be put into parts between the screw thread pieces 311a.COPYRIGHT: (C)2011,JPO&INPIT【課題】 プランジャーロッドの雄ネジ部とガスケットの雌ネジ部とが緩むのを防止できると共に、ガスケットのシール部が変形するのを抑制できるプランジャーロッド及びシリンジを提供する。【解決手段】 並設される複数のネジ片311a,311a間に配置され、ベース体33の外周部から突出する突出部34を備え、突出部34は、雌ネジ部21のネジ山211と係合すべく、雄ネジ部31のネジ溝312内に位置する係合部341を備えると共に、係合部341と係合することで弾性変形する雌ネジ部21のネジ山211を、ネジ片311aとの間に逃がすべく、各ネジ片311aと離間して配置されることを特徴とする。【選択図】 図5
