INSERTION APPARATUS, AND METHOD OF ILLUMINATING INSIDE OF SUBJECT

An insertion apparatus includes: an insertion portion including, a first conduit having a first opening, an illumination chamber having a second opening, an optical fiber configured to guide and radiate an illumination light, and an illumination lens. The first conduit is in fluid communication with an outside of the insertion portion via the first opening. The illumination chamber is configured to fluidly communicate with a peripheral part of the first conduit via the second opening. A distal end of the optical fiber is located inside of the illumination chamber. The illumination lens is configured to radiate the illumination light to the outside of the insertion portion.