PURPOSE: To reduce both deterioration of system processing performance and system faults by sending a start signal for recording and the file number of recording destination to a file controller and writing successively the record data to one of files with control of a selection circuit, a storage circuit and a replacement circuit.

CONSTITUTION: An input/output circuit 11 of a file controller 3 receives a command for start of recording action and the file number of the recording destination and sends them to a control circuit 8. The circuit 8 delivers a selection signal to a selection circuit 7, and the circuit 7 selects an address from a storage device 6 and reads its holding contents to a replacement circuit 9. The circuit 9 delivers the read-out contents to the circuit 8 and at the same time increases the holding contents by (1). The circuit 8 transfers the read-out contents to a connection circuit 10 as well as files 4 and 5. Either one of these files accepts the contents and writes the data sent from a data processor 1 or 2 to the corresponding address as a code address of a file of the recording destination.