An optical device includes: a multilayer structure substrate on which plural insulating layers are stacked and a wiring pattern is formed between layers; a recessed part for exposing the wiring pattern between the layers by cutting off a part of the multilayer structure substrate; an optical element mounted within the recessed part in electric conduction to the wiring pattern exposed by the recessed part; and an optical waveguide member forming an optical path for the optical element and guiding light along a surface of the multilayer structure substrate.