An optical input/output (I/O) bus system for connecting a plurality of external devices with a central processing unit (CPU) or memory in a specific system using an optical signal is provided. The optical I/O bus system includes a serializer and deserializer (SerDes) connected with the CPU or memory, and configured to divide a serial electrical signal into parallel electrical signals or combine parallel electrical signals into a serial electrical signal, a photoelectric converter prepared between the SerDes and the external devices, and configured to convert the serial/parallel electrical signals into an optical signal or an optical signal into an electrical signal, a plurality of optical transmission means disposed in parallel to transfer the optical signal converted by the photoelectric converter, an optical switch prepared between the photoelectric converter and the optical transmission means, and configured to switch to one of the optical transmission means to transfer the optical signal converted by the photoelectric converter to the optical transmission means according to an address of the optical signal, and a plurality of optical slots connected to the respective optical transmission means to connect the external devices so that the optical signal is input/output. In the optical I/O bus system, a high-capacity signal can be transferred without distortion, interference, and bottleneck using optical connection technology.