The present invention provides a process for producing an optical waveguide which comprises: disposing on an undercladding layer at least one member for forming an optical-path deflection plane; forming a photosensitive resin layer over the undercladding layer so as to at least partly cover the member for forming an optical-path deflection plane; subjecting the photosensitive resin layer to exposure and then development to thereby form at least one core layer; and forming an overcladding layer over the undercladding layer so as to cover the at least one core layer.