An optical communication module, comprising: (a) a photoelectric conversion device that is provided with a photoelectric conversion unit and a connector (21, 21a - 21d) on one surface of the photoelectric conversion device, wherein the photoelectric conversion unit performs a photoelectric conversion from an optical signal to an electrical signal or from an electrical signal to an optical signal with receiving or emitting light, and the connector (21, 21a - 21d) connects the photoelectric conversion device to another device; (b) an electric conductor (30, 30a - 30d) that is connected to the connector (21, 21a - 21d) of the photoelectric conversion device and is provided with an optical pass portion that passes light toward the photoelectric conversion unit of the connected photoelectric conversion device; (c) a transparency maintaining unit that comprises a transparent portion passing light between one side and another side, opposite to the one side, of the transparency maintaining unit and that holds the electric conductor (30, 30a - 30d), wherein a portion connecting the photoelectric conversion device is exposed at the one side; (d) a sealing means (40, 45 46) for sealing the photoelectric conversion device connected to the electric conductor (30, 30a - 30d), wherein (e) the transparency maintaining unit is provided with a recess portion that accommodates the photoelectric conversion device, (f) the sealing means (40, 45, 46) is provided with a cover that seals the recess portion, (g) the photoelectric conversion device performs a transmission of an optical signal between the one side and the other side through the transparent portion of the transparency maintaining unit and the optical pass portion of the electric conductor (30, 30a - 30d), and (h) a cylindrical portion that protrudes at the the other side of the transparency maintaining unit and internally fits a communication line for performing an optical communication, wherein: (i) the cylindrical portion comprises a cylindrical body and plural connection pins protruding from the cylindrical body, and (j) the transparency maintaining unit comprises a plurality of connection holes through which the connection pins extend between its one side and its other side in such a way that tip portions thereof protrude from the one side of the transparency maintaining unit. (a) a photoelectric conversion device that is provided with a photoelectric conversion unit and a connector (21, 21a - 21d) on one surface of the photoelectric conversion device, wherein the photoelectric conversion unit performs a photoelectric conversion from an optical signal to an electrical signal or from an electrical signal to an optical signal with receiving or emitting light, and the connector (21, 21a - 21d) connects the photoelectric conversion device to another device; (b) an electric conductor (30, 30a - 30d) that is connected to the connector (21, 21a - 21d) of the photoelectric conversion device and is provided with an optical pass portion that passes light toward the photoelectric conversion unit of the connected photoelectric conversion device; (c) a transparency maintaining unit that comprises a transparent portion passing light between one side and another side, opposite to the one side, of the transparency maintaining unit and that holds the electric conductor (30, 30a - 30d), wherein a portion connecting the photoelectric conversion device is exposed at the one side; (d) a sealing means (40, 45 46) for sealing the photoelectric conversion device connected to the electric conductor (30, 30a - 30d), wherein (e) the transparency maintaining unit is provided with a recess portion that accommodates the photoelectric conversion device, (f) the sealing means (40, 45, 46) is provided with a cover that seals the recess portion, (g) the photoelectric conversion device performs a transmission of an optical signal between the one side and the other side through the transparent portion of the transparency maintaining unit and the optical pass portion of the electric conductor (30, 30a - 30d), and (h) a cylindrical portion that protrudes at the the other side of the transparency maintaining unit and internally fits a communication line for performing an optical communication, wherein: (i) the cylindrical portion comprises a cylindrical body and plural connection pins protruding from the cylindrical body, and (j) the transparency maintaining unit comprises a plurality of connection holes through which the connection pins extend between its one side and its other side in such a way that tip portions thereof protrude from the one side of the transparency maintaining unit.