An illumination apparatus, comprising a light source unit, a rod-shaped light guide configured to guide light from the light source unit and emit the light from a light emitting surface, a covering member configured to contain the light guide, and a housing configured to contain the light source unit, the light guide, and the covering member, the light guide including a protruded portion configured to suppress a shift in a longitudinal direction, the covering member including an opening, and the housing including a receiving portion configured to receive the protruded portion of the light guide, wherein the protruded portion of the light guide is engaged with the receiving portion of the housing via the opening of the covering member.