An optical transmission module includes: an optical device including a light-emitting unit configured to output light of an optical signal； a wiring board including a first principal surface, and a second principal surface, the second principal surface on which the optical device is disposed； a holding member having a lower surface fixed to the first principal surface of the wiring board, and having an optical fiber through hole perpendicular to the lower surface； and an optical fiber inserted into the optical fiber through hole, and configured to transmit the optical signal, wherein the first principal surface of the wiring board has a recessed portion, and the holding member is fixed to the wiring board with a bonding agent in the recessed portion.
