The present invention causes bending to be possible at a small amount of traction force, and improves the compactness and control characteristics of a device. Provided is a joint mechanism (12a) provided with: a first member (13a) having a tubular shape and having a through hole (17)； a second member (13b) that is disposed at the tip side of the first member (13a) and that is provided in a manner able to reciprocate around a reciprocation axis line that intersects the central axis of the first member (13a)； a tubular guide sheath (21a, 21b) that penetrates the vicinity of the central axis of the through hole (17) and has flexibility such that the tip is affixed to the second member (13b)； an operation wire (22a, 22b) introduced to the tip side of guide sheath (21a, 21b)； and a folded-back section (20a, 20b) that is provided to a position of the second member (13b) decentered in the radial direction from the reciprocation axis line and that causes the operation wire (22a, 22b) introduced from the first member (13a) side via the guide sheath (21a, 21b) to undergo a U-turn to the first member (13a) side. The tip of the operation wire (22a, 22b) caused to U-turn at the folded-back section (20a, 20b) is affixed to a position decentered in the radial direction.La présente invention permet une courbure à une faible amplitude de force de traction, et améliore les caractéristiques de compacité et de commande d'un dispositif. L'invention concerne un mécanisme d'articulation (12a) qui comprend : un premier élément (13a) ayant une forme tubulaire et un trou traversant (17) ； un second élément (13b) qui est disposé sur le côté d'extrémité du premier élément (13a) et qui est placé de façon à réaliser un mouvement de va-et-vient autour d'une ligue d'axe de mouvement de va-et-vient qui coupe l'axe central du premier élément (13a) ； une gaine de guidage tubulaire (21a, 21b) qui pénètre au voisinage de l'axe central du trou traversant (17) et a une flexibilité de telle sorte que l'ex
