To facilitate optical signal transmission in a substrate in top surface incidence.

The silicone oxidized film 101b of an SOI substrate 101 is composed of a first depth part 101b1, a second depth part 101b2 that is deeper than the first depth part, and an inclined part 101b3 that connects the first and the second depth part. The inclined part 101b3 is used as a reflection mirror constituting the passage of optical signals, while an optical signal from a surface-emitting laser chip 105 is guided to the inclined part 101b3 through an SiO2 through hole 104a. Then, this optical signal is reflected on the inner surface of the inclined part 101b3 and subsequently guided on the second depth part 101b2 of the silicone oxidized film 101b as an optical waveguide. Thereafter, this optical signal is again reflected on the inner surface of the inclined part 101b3 of the silicone oxidized film 101b and inputted in the optical signal input part 108b of a PD chip 108 through an SiO2 through hole 104b.