An optical transmission module includes an optical element including a light-emitting section configured to output light of an optical signal, a hollow cylindrical body joined perpendicularly to a light output surface of the optical element, a wiring board, on a first principal surface of which the optical element is mounted and through a hole of which the hollow cylindrical body is inserted, and an optical fiber configured to transmit the optical signal, a distal end portion of which is inserted into the hollow cylindrical body.