An LSI package having an optical interface is mounted on a surface of a photoelectric wiring board. The photoelectric wiring board and the optical interface are optically connected with sufficient precision. A wiring board side guide member including socket pins and guide pins is soldered and fixed onto the photoelectric wiring board including an optical transmission line, a guide pin, and a mirror. An optical interface side guide member having a fitting hole is glued to the optical interface. The optical interface is mounted on an interposer of the LSI package. The guide pin of the photoelectric wiring board is fitted into the fitting hole formed through the interposer. The guide pin of the guide member is fitted into the fitting hole of the guide member. As a result, position alignment between the optical interface and the photoelectric wiring board is conducted with high precision.