An optical waveguide includes: a core portion through which light propagates; a cladding portion enclosing the core portion along a direction of light propagation, and a colored resin for position recognition marking, the optical waveguide having substantially planar outer surfaces including principal surfaces thereof, and the colored resin being embedded in the optical waveguide at a position that does not substantially overlap the core portion when viewed from a direction perpendicular to a principal surface of the optical waveguide and does not substantially contact the core portion.