A system and method for processing an extraordinarily large amount of data is configured using ordinary versatile computers of relatively slow data processing speed. Tasking is shared to plural computers or processors connected to a system bus; a shared storage device provided in common for these processors is made up of plural memory banks connected to the system bus; data transferred between the processors and the memory banks are divided into predetermined amounts of divisional data; the divisional data are processed simultaneously in parallel fashion; and each memory bank is occupied simultaneously in parallel fashion in response to each memory request from each processor. An arbitrator is provided for acting on a single memory request in accordance with a predetermined priority order in the case where plural memory requests are outputted simultaneously to the same memory bank.