An optical transmission module is configured such that: a first optical device is provided on an upper surface of an optical waveguide substrate； a second optical device is provided on a lower surface of the optical waveguide substrate； a V-groove is formed on an end face of the optical waveguide substrate, the V-groove including a first reflective face and a second reflective face as wall faces； the first optical device is optically coupled with an optical waveguide via the first reflective face； and the second optical device is optically coupled with the optical waveguide via the second reflective face.
