PURPOSE: To prevent the reduction in the processing performance, by enabling to execute the readout operation at each CPU at the same time, at a memory device commonly used in a plurality of data devices.

CONSTITUTION: A memory device 2 has N sets of copy memories 3aW3c to N sets of CPUs 1aW1c, the copy memories 3aW3c are used as one storage block, one storage block is provided to the CPUs 1aW1c for readout only, and at writing for data renewal, one of the CPUs 1aW1c with write request is selected to write the same data to each storage block at the same time, and an apparent one input/multi-output memory device can be realized.