We have designed a parallel processor system with hundreds of processors specific for Monte-Carlo analysis. This system has the ring-bus architecture. The performance of several Gflops is expected in this system according to the computer simulation. However, it was revealed that the data transfer speed of the bus has to be increased more dramatically in order to further increase the performance. Then, we propose introducing the optical interconnection into the parallel processor system to increase the data transfer speed of the buses. The double ring- bus architecture is employed in this new parallel processor system with optical interconnection. The free-space optical interconnection and the optical waveguide are used for the optical ring-bus. It was confirmed in simulation that the optical data transfer operation and the memory store operation into FIFO in the optical ring-bus interface unit can be successfully performed.