A rotation shaft 18, a bending operation knob 4, a fixed shaft, two movable disks 11 and 12, a fixed disk 14, a cam member 15, a resistance giving member 17 and a fixing lever 5 are included. The resistance giving member 17 has a rocking portion 17t that fixes a rotation position of the cam member 15 in a second position of the movable disks 11 and 12 by abutting onto an inner circumferential face of a protruding portion 15t of the cam member 15 that moves with rotation in one direction of the cam member 15, with an urging force, and is rockable in a diameter direction.
