[Problem] To provide an operation member whereby it is possible to efficiently transmit an extend-retract movement of a push-pull member to a long piece member, and whereby it is possible to effect overall miniaturization of a device, as well as a medical instrument comprising the operation member. [Solution] Provided is an operation member, comprising: a first movement member (21) and a second movement member (22) which are positioned on a base end side of a long piece member (10), and which are disposed to be capable of relative approach and separation in the axial direction of the long piece member a push-pull member (30) further comprising a first connection part (31) which is connected to the first movement member, a first stretch part (33) which is stretched from the first connection part toward the leading end side in the axial direction of the long piece member, a second connection part (32) which is connected to the second movement member, and a second stretch part (34) which is stretched from the second connection part toward the leading end side in the axial direction of the long piece member, and which is push-pulled and moves in the axial direction of the long piece member with the movements of the first movement member and the second movement member and a manipulation member (40) for manipulating the movement of the first movement member and the second movement member.La présente invention a pour but de proposer un élément dactionnement au moyen duquel il est possible de transmettre efficacement un mouvement dextension-rétraction dun élément de poussée-traction à un élément allongé, et au moyen duquel il est possible deffectuer une miniaturisation globale dun dispositif, ainsi quun instrument médical comprenant lélément dactionnement. A cet effet, linvention porte sur un élément dactionnement, comprenant : un premier élément de déplacement (21) et un second élément de déplacement (22) qui sont positionnés sur un côté extrémité de base dun élément allon
