An optical waveguide, an optical printed circuit board equipped with the optical waveguide, and methods of manufacturing the optical waveguide and the optical printed circuit board are disclosed. The optical waveguide can include: a first cladding layer; a core formed on the first cladding layer; an alignment pattern, having a predefined positional relationship to the core, formed on the first cladding layer; a target mark formed on the alignment pattern to indicate a position of the alignment pattern; and a second cladding layer formed on the first cladding layer to cover the core, the alignment pattern, and the target mark. In such an optical waveguide, circuit patterns, etc., formed over the second cladding layer may be precisely and efficiently aligned with the core.