A photoelectric conversion device comprises a high-refractive-index portion at a position close to a photoelectric conversion element therein. And, the high-refractive-index portion has first and second horizontal cross-section surfaces. The first cross-section surface is at a position closer to the photoelectric conversion element rather than the second cross-section surface, and is larger than an area of the second cross-section surface, so as to guide an incident light into the photoelectric conversion element without reflection.