PURPOSE: To provide the directory memory system multiprocessor which does not depend upon the number of processing elements and is realized with small memory capacity.

CONSTITUTION: In the common memory type multiprocessor which has information on processing elements 20-27, holding duplicates of memory data, in a directory memory 401 attached to a data memory 402, the processing elements 20-27 are grouped and directory information is held, group by group, to prevent the directory memory 401 from increasing as the number of the processing elements increases. Consequently, the directory system multiprocessor which has high memory efficiency is obtained. Therefore, a large-scale multiprocessor can easily be structured and the performance of the system can be improved.