Optical transmission module

An optical transmission module includes: a main substrate having a front surface and a back surface; an optical connector having a connector substrate; a first transparent substrate disposed between the connector substrate and the main substrate; a heat source element disposed between the connector substrate and the back surface of the main substrate, and electrically connected to the main substrate; one or a plurality of wirings electrically connecting the heat source element to the main substrate, and each configured to transfer heat generated from the heat source element and the first transparent substrate, to the main substrate; a first special region preventing the heat generated from the heat source element and the first transparent substrate, from being transferred to the connector substrate; and a second special region providing a function of transferring the heat generated from the heat source element and the first transparent substrate.