| CPC B25J 18/06 (2013.01) [A61B 2017/2905 (2013.01); A61B 2034/301 (2016.02); A61M 25/0138 (2013.01)] | 5 Claims |

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1. A bending structure being bendable with respect to an axial direction, comprising:
an outer coiled part formed of a wire which is wound in a coiled shape to have a plurality of coils in the axial direction; and
an inner coiled part formed of a wire which is wound in a coiled shape to have a plurality of coils in the axial direction and located inside the outer coiled part, wherein
the outer coiled part has a plurality of gaps to distance adjacent coils in the axial direction,
the coils of the inner coiled part are provided so as to correspond to the gaps of the outer coiled part and fit between the adjacent coils of the outer coiled part while being in contact with the adjacent coils of the outer coiled part, and
a dimension (P) is set in a range meeting π(R)/4(N)≤P<(d)−π(R)/4(N) in which (P) is the dimension of a gap of the outer coiled part in the axial direction in a free state, (N) is the number of turns of the outer coiled part, (R) is a diameter of the outer coiled part, and (d) is a wire diameter of the wire of the inner coiled part.
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