An insertion portion includes a holding member that holds an observation portion, and a tubular bending portion. A small-diameter portion of the holding member is fitted into an inside surface of a distal end side portion of the bending portion. A hole portion is provided in the bending portion. A concave portion is provided at the small-diameter portion. A screw member penetrates the hole portion by screw-fastening, and a distal end side thereof is housed in the concave portion. A diameter of the concave portion is larger than an outside diameter of the screw member. A length obtained by adding a depth of the concave portion and a thickness of the distal end side portion of the bending portion is greater than an axial direction length of the screw member. The screw member is held in a non-contacting state with respect to the concave portion in the hole portion.
