PURPOSE: To improve the processing performance and to reduce the load of a data processor by performing the control of a file group which is shared by plural data processors by a file control processor for each block constituting a file.

CONSTITUTION: Plural data processors 1-1W1-n share plural files 1-1W1-m. A file control processor 3 is connected to the processors 1-1W1-n, and the writing or reading is carried out by exclusive control for file groups with each block. For instance, when the processor 1-2 replaces a block 211 in a file 2-2, an exclusive control is first commanded to the processor 3. Then the processor 3 checks the corresponding block whether it is used or not by another data processor if it is used, then rejects the replacement until the use of the block is finished. The processor 3 generates a new block within a file when the indicated block is not found in the file. In such a way, the processing performance is improved.