The present invention has an object to provide a bending angle adjustment mechanism which realizes reduction in the number of components and unitized structure and which contributes to simplification of the assembly process and reduction in the manufacturing cost and contributes to improvement of workability of readjustment and the like at the time of overhauling. In order to achieve the object, a bending angle adjustment mechanism 30 for an endoscope 1 includes: a rod member 54 that is provided to extend in a longitudinal direction of the insertion portion 8 and has a threaded portion formed on a surface in the longitudinal direction； a plate member 52 that is provided to be parallel to the longitudinal direction of the rod member and has both ends through which the rod member is inserted, the both ends being formed by being bent in a substantially perpendicular direction； an adjustment piece 55 that is engaged with the threaded portion of the rod member； a guide member 53 that is disposed to be parallel to the rod member and the plate member, and includes, in the longitudinal direction of the insertion portion, a guide path 53xb that allows the long member 32 to pass and a guide surface 53xa that guides the adjustment piece； and a rotation preventing member 51 that prevents the rod member from rotating with respect to the guide member, with the longitudinal direction as an axis, wherein the guide member has at least one surface that is sandwiched and fixed between the adjustment piece and the plate member, the at least one surface not being parallel to the guide surface of the guide member.
