An endoscope comprises: a forward-viewing observation window in which an objective lens for forward-viewing is provided at a distal end of an insertion portion； a light-guiding plate arranged at a forward-viewing illuminating window that is formed on an outer circumferential side of the forward-viewing observation window and has a C-ring shape for guiding light falling on an incident surface formed by cutting out an outer circumferential part on a lower side of the observation field of view for forward-viewing, the light-guiding plate having a reflective surface formed on a back face to diffuse and reflect light and a transmissive surface formed on a front face to transmit light and make light exit to the observation field of view for forward-viewing as illuminating light； and a light exit portion that makes light exit to fall on the incident surface of the light-guiding plate, wherein the endoscope comprises a wedge-shaped reflective surface formed by cutting out into a wedge shape from the back face toward the front face of the light-guiding plate at a position on an upper side of the light-guiding plate.
