Optical elements (light sources 16 or photodetectors 18) are arranged in a two-dimensional array, and the relative positional relationship between the optical elements and optical waveguides 12 is defined such that optical waveguides 12 extend between the optical elements in the two-dimensional array substantially parallel to substrate 19 for increased parallelism. Micromirrors 15 are disposed in respective optical waveguides 12 to bend light beams through 90 degrees to realize a highly efficient optical coupling between the optical elements and optical waveguides 12. The optical waveguides are stacked in multiple stages, and light beams are lead to the optical waveguides in the multiple stacks through micromirrors 15 across the stacked plane of the optical waveguides, thereby realizing parallel connection between the two-dimensional array of optical elements and a two-dimensional array of optical waveguides. There is thus provided a connection structure between the optical elements and optical waveguides 12, which is small in size and high in efficiency, and is of high parallelism.