The tubular body, a plurality of operation lines, an operation part body provided at the proximal end of the tubular body, a bending operation part for bending the distal part of the tubular body, and a path of the operation line in the bending operation part are defined. A medical device including a route defining unit. When the bending operation part is in the fixed position, the operation line is in a relaxed state, and when it is in the operation position, the operation line is in a tensioned state, and further prevents the operation line from deviating from the route defined by the route defining unit. A departure prevention member.管状本体と、複数の操作線と、管状本体の基端部に設けられた操作部本体と、管状本体の遠位部を屈曲させる屈曲操作部と、屈曲操作部内における操作線の経路を規定する経路規定部と、を備えた医療機器。屈曲操作部が固定位置にあるときは、操作線は弛緩状態となるとともに、操作位置にあるときは、緊張した状態となり、更に経路規定部により規定される経路から操作線が逸脱することを防止する逸脱防止部材と、を備える。
