Provided is an optical integrated device comprising a first waveguide that is formed on a substrate and includes a first optical path; an electrode formed on the first waveguide; a second waveguide that is formed on the substrate and includes a second optical path; and a transparent waveguide that is formed on the substrate between the first waveguide and the second waveguide, and includes a transparent core that serves as an optical path and is formed of a material having higher bandgap energy than the first optical path. The electrode is formed above the first waveguide and is not formed above the transparent waveguide, and elements including the first waveguide are optically active elements that operate according to current injected thereto.