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.