PURPOSE: To easily maintain the consistency of a cache memory without deteriorating the processing performance of a processor by setting access from the processor to be enabled and making a direction transferred from the other device freeze.

CONSTITUTION: A control register 9 executes control in such a way that access is not executed as to access from the direction to which prohibition is instructed and writing is executed as to access from a direction to which freezing of the tag part 1 is instructed, and a data part 2 is updated at the time of tag coincidence and the tag part 1 and the data part 2 are not updated at the time of tag part dissidence. Namely, access from the processor is set enabled and the direction transferred from the other device is set frozen. The consistency of the cache memory is maintained without deteriorating the processing capacity of the processor.