A structure which stably achieves electrical coupling, and is capable of efficient optical coupling is provided. Optical coupling is achieved with the lower surface of an opto-electric package and the upper surface of an opto-electric hybrid board. On the other hand, electrical connection is achieved by means of contact between electrodes on the side surfaces of the opto-electric package and electrodes on the inner-wall side surfaces of a socket mounted on the opto-electric hybrid board. The electrodes are in electrical contact with electrical wiring.