An endoscope according to the present invention includes: a first image pickup optical system for observing a first observation direction, a second image pickup optical system for observing an observation a second observation direction, a light guide guiding illumination light, and an illumination optical system including a ring-shaped portion illuminating the first observation direction, an incident surface being in contact with an end surface of the light guide to receive the illumination light, and two reflecting surfaces disposed at a position opposite to the incident surface, having inclinations in two directions with respect to a surface orthogonal to the longitudinal direction of the insertion portion, disposed so as to face each other, and reflecting the illumination light incident from the light guide toward directions along tangent lines of the ring-shaped portion of the illumination optical system, to cause the illumination light incident to inside of the illumination optical system.