A light guiding optical system includes a light guide configured to guide light from an entrance end to an exit end by internally reflecting the light a plurality of times, and an optical unit configured to condense the light emitted from the exit end of the light guide in a first section. The exit end of the light guide has an aperture that has a size in a first direction perpendicular to the first section, which is larger than a size in a second direction perpendicular to the first direction.
