PROBLEM TO BE SOLVED: To provide a medical device and a treatment method capable of preventing the needle part from projecting more than needed and inhibiting miss-puncture, thereby increasing safety.SOLUTION: A medical device 10 is inserted into a lumen of a living body to puncture living tissue and keeps the formed puncture open, comprising: a flexible elongated needle part 30； a flexible tubular dilator 40 for receiving the needle part 30 in such a manner that the needle part can project to a distal side； and a force generation part 74 provided on a proximal side of the dilator 40 to cause a force directed toward a proximal side to be exerted to the needle part 30 from a state in which the needle part 30 is projected from an elongated body.SELECTED DRAWING: Figure 1COPYRIGHT: (C)2020,JPO&INPIT【課題】針部が必要以上に突出せず、誤穿刺を抑制して安全性を高める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】生体管腔内に挿入されて生体組織を穿刺し、穿刺して空けた孔を広げた状態で保持するための医療デバイス１０であって、可撓性を備えた長尺な針部３０と、針部３０を遠位側へ突出可能に収容する可撓性を備えた管状のダイレータ４０と、ダイレータ４０の近位側に設けられ、針部３０が長尺体から突出した状態から、針部３０に近位側へ向かう力を作用させる力発生部７４と、を有する。【選択図】図１
