In a first bending piece (51), a second bending piece (52), and a third bending piece (53) disposed sequentially from an extreme end side and manipulation wires (56a, 56b) for rotating the first bending piece (51), manipulation wires (57a, 57b) for rotating the second bending piece (52), and manipulation wires (58a, 58b) for rotating the third bending piece (53), the manipulation wires (56a, 56b) and the manipulation wires (57a, 57b) are disposed concentrically with respect to the direction of a center axis L.