To provide a bending structure which can secure sufficient flexibility and axial rigidity, and to provide a joint function part and an instrument for an operation support robot.SOLUTION: A bending structure includes: an outer coil part 5 comprising a wire 5a wound into a coil shape and having multiple winding parts 5b in an axial direction； and an inner coil part 7 comprising a wire 7a, which is wound into a coil shape and has multiple winding parts 7b in the axial direction, and located in the outer coil part 5. The outer coil part 5 has multiple gaps 5c formed by separating the adjacent winding parts 5b. In the inner coil part 7, the winding parts 7b are provided corresponding to the gaps 5c of the outer coil part 5 and fit into spaces between the winding parts 5b while contacting with the adjacent winding parts 5b of the outer coil part 5.SELECTED DRAWING: Figure 1【課題】十分な可撓性と軸方向の剛性とを確保することが可能な屈曲構造体、関節機能部、及び手術支援ロボット用インスツルメントを提供する。【解決手段】コイル状に巻かれて軸方向に複数の巻部５ｂを有する線材５ａからなる外コイル部５と、コイル状に巻かれて軸方向に複数の巻部７ｂを有する線材７ａからなり、外コイル部５内に位置する内コイル部７とを備え、外コイル部５は、隣接する巻部５ｂ間を離間させた複数の隙間５ｃを有し、内コイル部７は、巻部７ｂが外コイル部５の隙間５ｃに対応して設けられ、外コイル部５の隣接する巻部５ｂに接触しつつ当該巻部５ｂ間に嵌合する。【選択図】 図１
