An optical waveguide device includes a substrate on which an optical waveguide is formed, and a reinforcing block disposed on the substrate, along an end surface of the substrate on which an input portion or an output portion of the optical waveguide is disposed, in which an optical component that is joined to both the end surface of the substrate and an end surface of the reinforcing block is provided, a material used for a joining surface of the optical component and a material used for the substrate or the reinforcing block have at least different linear expansion coefficients of a direction parallel to the joining surface, and an area of the joining surface is set to be smaller than a maximum value of a total of areas of cross sections of the substrate and the reinforcing block parallel to the joining surface.