PROBLEM TO BE SOLVED: To provide an endoscope which is excellent in operability and durability by achieving to make loads applied on built-in matters with high flexural rigidity uniform regardless of a bending direction of a bending portion.SOLUTION: An outer diameter of a tube 54 with high rigidity is set at &phgrA, and an inner diameter of a bending tube 52m is set at &phgrB that is larger than the outer diameter of the tube 54. In setting a curvature radius R1 of a tube central axis 54a in a first bending state in which an outer peripheral surface of the tube 54 is brought into contact with an inner surface of the bending tube 52m located on a side of a bending portion lower region 41Sd in a cross section perpendicular to a central axis 41a of an insertion portion 41, and a bending portion 48 is bent in such a manner that the lower region 41Sd is located inside the central axis 41a of the insertion portion 41 and a curvature radius of the tube central axis 54a in a second bending state in which the bending portion is bent in such a manner that the lower region is located outside to be identical, a central axis curvature radius in the first bending state is set at a first dimension C, and a central axis curvature radius in the second bending state is set at a second dimension D. A difference between the first dimension C and the second dimension D conforms to a difference between the inner diameter &phgrB and the outer diameter &phgrA.
