PROBLEM TO BE SOLVED: To provide an insertion part flexible tube for an endoscope which is easy to operate since flexibility decreases when the endoscope is pressed into the body and flexibility increases when drawn back from inside the body without causing any safety problem.SOLUTION: Many short cylindrical articulation rings 10 are placed in series while they are abutted on one another, and an outer sheath 20 is provided with elasticity and individually engaged with the respective articulation rings 10 so that: when compressive force acts on the articulation rings, friction resistance acting on the respective abutment parts of the adjacent articulation rings 10 increases and the respective abutment parts are hard to bend when tensile force acts on the articulation rings, the friction resistance decreases and the respective abutment parts are easily bent.COPYRIGHT: (C)2013,JPO&INPIT【課題】体内への押し込み操作時には可撓性が小さくなって、体内からの引き戻し操作時には可撓性が大きくなり、しかも安全性に問題が生じるおそれがなくて操作も簡単な内視鏡の挿入部可撓管を提供すること【解決手段】多数の短筒状の関節輪10が直列に互いに当接した状態に配置されて、それに圧縮力が作用すると、隣り合う関節輪10どうしの各当接部に作用する摩擦抵抗が大きくなって各当接部が曲がり難くなり、引張力が作用すると摩擦抵抗が小さくなって各当接部が曲がり易くなるように、外皮20が、伸縮性を備えていて各関節輪10と個別に係合している。【選択図】 図1
