PROBLEM TO BE SOLVED: To provide an actuation member and a medical device highly efficiently transmitting forward/backward movements of a push/pull member to a long member and enabling downsizing.SOLUTION: An actuation member 5 comprises: a push/pull member 30 that is disposed at a proximal side of a long member 10, includes a first move part 31 and a second move part 32 relatively movable in the axial direction of the long member 10, a first extension part 33 extended from the first move part 31 towards a distal side of the long member 10, and a second extension part 34 extended from the second move part 32 towards the distal side of the long member 10, and is pushed/pulled axially with the movement of the respective move parts 31 and 32； and an operation member 40 that is provided rotatably about a shaft in the direction intersecting with the axial direction of the long member 10 and operates the movement of the respective move parts 31 and 32. At least one of the respective move parts 31 and 32 and the operation member 40 includes a first guide groove 41 for guiding the movement of the first move part 31, and a second guide groove 42 for guiding the movement of the second move part 32.【課題】押し引き部材の進退移動を長尺部材に効率よく伝達でき、小型化が可能な作動部材および医療器具を提供する。【解決手段】作動部材５は、長尺部材１０の基端側に配置され、長尺部材１０の軸方向に相対移動可能な第１移動部３１および第２移動部３２、第１移動部３１から長尺部材１０の先端側へ延伸された第１延伸部３３、および第２移動部３２から長尺部材１０の先端側へ延伸された第２延伸部３４、を備え、各移動部３１、３２の移動に伴い軸方向に押し引きされる押し引き部材３０と、長尺部材１０の軸方向と交差する方向の軸を回転中心として回転可能に設けられ、各移動部３１、３２の移動を操作する操作部材４０と、を有し、各移動部３１、３２と操作部材４０との少なくとも一方には、第１移動部３１の移動を案内する第１案内溝４１と、第２移動部３２の移動を案内する第２案内溝４２とが設けられる。【選択図】図２
