An optical module has an optical element which transmits or receives an optical signal, an optical transmission line optically coupled to the optical element to transmit the optical signal, and a board to which at least one end portion including an incident and outgoing port of the optical signal in the optical transmission line and the optical element are fixed. A wall facing a side surface of the optical transmission line is provided in the board. A first space is provided between the board and the optical transmission line, and a second space is provided between the side surface of the optical transmission line and the wall. The first and second spaces are filled with a bonding agent.