PURPOSE: To facilitate adjustment for the degree of tightening for operating wires by installing the basic edge part of a guide pipe in a shift-disabled manner at the basic edge part of an insertion part, and installing the insertion part so as to be relatively shiftable in the longitudinal direction of the insertion part for an operation part and installing a fixing means for the insertion part and the operating part in the relatively shift-disabled manner.

CONSTITUTION: An operating wire 8a or 8b is pulling-operated by actually turning an operating knob 11, and a curved part 4 is curved. If a play or chattering is generated, or the degree of curvature of the curved part 4 for the turning quantity of the operating knob 11 is small, a screw 6 is loosened, and an insertion part 3 is pulled outside, and the tightening for the operating wire 8a, 8b is strengthened, and the screw 6 is tightened again, and then the insertion part 3 is fixed on an operating part 2. When an extremely large force is necessary in the case when the operating knob 11 is turned, it is judged that the degree to tightening for the operating wire 8a, 8b is large, and the insertion part 3 is pushed in a little, and the degree of tightening for the operating wire 8a, 8b is loosened, and the insertion part 3 is fixed on the operation part 2 again. Accordingly, in consideration of the curving operation performance of an endoscope 1, the position of the insertion part 3 for the operation part 2 is determined so that the degree of tightening for the operating wire 8a, 8b is made optimum.