Abstract: An optical receptacle with low transmission loss, which is connectable with an optical plug, is provided. The optical receptacle includes a photoelectric conversion module having the capability of making photoelectric conversion between light signals and electrical signals, and a module housing. The photoelectric conversion module is a molded interconnect device (MID), which is provided with a module body having a post, an optical device mounted on the post, and an electrical circuit mounted on the module body. The module housing has a tubular projection, into which an end of the optical fiber supported by the optical plug can be inserted. When the optical plug is connected with an optical receptacle, the end of the optical fiber is positioned in the tubular projection so as to be in a closely opposing relation to the optical device mounted on the post.