ObjectTo provide an optical waveguide device capable of suppressing an excess optical loss at a low level.MeansAn optical waveguide device including a substrate having an electro-optic effect, an optical waveguide 1 formed on the substrate, and a control electrode having a signal electrode 2 and ground electrodes 3 and 4 for controlling light waves that propagate through the optical waveguide, in which the signal electrode 2 has, in an intersection portion in which the signal electrode 2 is disposed on the optical waveguide 1, a narrow portion at which a width of the signal electrode 2 is narrower than those of portions before and after the intersection portion.