PROBLEM TO BE SOLVED: To quickly transfer heat of a heat generator incorporated in the distal end of an insertion part which is inserted into the body cavity, to the back side in an axial direction of the insertion part, by using an operation wire.SOLUTION: An imaging element 60 is incorporated at the distal end of the insertion part. In a circuit board 61 mounting the imaging element 60, one end 70a of a heat transfer member 70 is attached. The other end 70b is attached to the operation wire 44. Operation wires 44, 46 are formed in a fiber shape from multilayer carbon nanotubes having characteristics of high heat conductivity and high tensile strength and allowed to slide to a wire guide 69 of a joint piece 65, inside a curved part 24. Heat generated by the imaging element 60 is transferred to the operation wire 44 via the circuit board 61 and heat transfer member 70, and the heat is radiated to the joint piece 65 from the operation wire 44.
