An optical waveguide device includes a first substrate, where the first substrate includes a first plate and an optical waveguide region disposed on the first plate, and where the optical waveguide region includes a core for transmitting light and a cladding surrounding the core. The optical waveguide device further includes a second substrate, where the second substrate includes a second plate having a spacer. Additionally, a surface including the optical waveguide region of the first substrate opposes a surface including the spacer of the second substrate, the spacer is formed the region which is out of the core of the first substrate, a top surface of the spacer is in contact with the first substrate, the first substrate and the second substrate are bound with adhesive material, and the entire surface of the core is in contact with the adhesive material.