An optical memory system according to example embodiments includes a plurality of memory modules, each memory module including a plurality of memory devices; a light source; a light distribution unit connected to the light source through a first optical transmission line; a plurality of second optical transmission lines connected between the light distribution unit and the plurality of memory modules; a plurality of electrical to optical converters, each connected to at least one of the second optical transmission lines; and a plurality of output optical transmission lines connected to the plurality of electrical to optical converters, each output optical transmission line for outputting an electrical to optical converted signal.