A light transmission module includes a light transmission path for transmitting light, an optical element including a light emitting and receiving surface for optically coupling with the light transmitted by the light transmission path, and being formed with a light emitting and receiving point having a function of photoelectric conversion and an electrode pad on the light emitting and receiving surface. The light transmission module further includes a substrate mounted with the optical element and an electrical wiring and an electrical connecting member for electrically connecting the electrode pad and the electrical wiring. The substrate includes a wiring exposed surface where the electrical wiring is exposed. The electrical connecting member is made of solidified object of a liquid conductive material arranged to contact the electrical wiring, which is exposed at the wiring exposed surface, and the electrode pad.