An endoscope comprising: a tube-like inserted portion having a distal end; two light guiding members that are accommodated in the inserted portion and are configured to guide illumination light to the distal end; and two plano-concave lenses configured to radiate the illumination light guided by each light guiding member, wherein, in each plano-concave lens, an outer surface is formed of a flat surface and an inner surface is formed of a curved surface; and an objective optical system configured to collect light from a region illuminated by the plano-concave lenses, wherein the plano-concave lenses and the objective optical system are disposed at the distal end of the inserted portion, and wherein the two plano-concave lenses are disposed at positions that are substantially mirror symmetrical relative to a plane that passes through an optical axis of the objective optical system, and a shoulder portion of the distal end and a respective outer surface of the plano-concave lenses located at the shoulder portion are inclined so as to become narrower toward the tip, characterised in that: an end portion of each light guiding member facing the plano-concave lenses is configured to extend substantially parallel to the optical axis of the objective optical system; and in that: when viewed from an optical axis direction of the objective optical system, an angle formed between i) a surface normal of each flat surface of the plano-concave lenses and ii) an optical axis of the respective light guiding member is 30° or less, and in that: in each plano-concave lens, at substantially the center of the outer surface of the plano-concave lens, the curvature of the curved surface in the inclination direction is formed to be larger than the curvature of the curved surface in a direction orthogonal to an inclination direction of the flat outer surface. a tube-like inserted portion having a distal end; two light guiding members that are accommodated in the inserted portion and are configured to guide illumination light to the distal end; and two plano-concave lenses configured to radiate the illumination light guided by each light guiding member, wherein, in each plano-concave lens, an outer surface is formed of a flat surface and an inner surface is formed of a curved surface; and an objective optical system configured to collect light from a region illuminated by the plano-concave lenses, wherein the plano-concave lenses and the objective optical system are disposed at the distal end of the inserted portion, and wherein the two plano-concave lenses are disposed at positions that are substantially mirror symmetrical relative to a plane that passes through an optical axis of the objective optical system, and a shoulder portion of the distal end and a respective outer surface of the plano-concave lenses located at the shoulder portion are inclined so as to become narrower toward the tip, an end portion of each light guiding member facing the plano-concave lenses is configured to extend substantially parallel to the optical axis of the objective optical system; when viewed from an optical axis direction of the objective optical system, an angle formed between i) a surface normal of each flat surface of the plano-concave lenses and ii) an optical axis of the respective light guiding member is 30° or less, in each plano-concave lens, at substantially the center of the outer surface of the plano-concave lens, the curvature of the curved surface in the inclination direction is formed to be larger than the curvature of the curved surface in a direction orthogonal to an inclination direction of the flat outer surface.