PROBLEM TO BE SOLVED: To provide a medical device and a treatment method in which a wire inserted from the outside of the body can be folded back so as to surround the distal side of a living tissue in a living body easily and with minimum invasion.SOLUTION: A medical device 10 for folding back a wire 50 inserted from the outside of the body so as to surround the distal side of a living tissue in a living body includes: a shaft part 20 including a tubular bent part 23 bendable in one direction, a distal opening 27 where a main lumen 21A communicated with the end part on the distal side from the proximal side is open, and a proximal opening 26 where the main lumen 21A communicated with the proximal side as compared with the bent part 23 or the proximal part of the bent part 23 from the proximal side is open； and an operation wire 30, the tip of which is connected to the distal side as compared with the bent part 23 of the shaft part 20 or the distal part of the bent part 23, and which causes the bent part 23 to be bent by a pulling operation on the base end side.SELECTED DRAWING: Figure 1【課題】低侵襲かつ容易に、体外から挿入した線材を生体内で生体組織の遠位側を囲むように折り返すことができる医療デバイスおよび処置方法を提供する。【解決手段】体外から挿入する線材５０を生体内で生体組織の遠位側を囲むように折り返すための医療デバイス１０であって、一方向へ曲がることが可能な管状の屈曲部２３が設けられ、遠位側の端部に近位側から連通する主ルーメン２１Ａが開口する遠位開口部２７が設けられ、屈曲部２３よりも近位側または屈曲部２３の近位部に近位側から連通する主ルーメン２１Ａが開口する近位開口部２６が設けられたシャフト部２０と、シャフト部２０の屈曲部２３よりも遠位側または屈曲部２３の遠位部に先端部が連結され、基端側における牽引する操作により屈曲部２３を屈曲させる操作ワイヤ３０とを有する。【選択図】図１
