PURPOSE: To provide the multiple writing filing system which can take backup data from a relevant filing device without exerting any influence upon another device while operating the system.

CONSTITUTION: First-third filing devices 10, 20 and 30 are the filing systems of triple writing to write the same data, are respectively internally provided with control parts 11, 21 and 31 and are also equipped with control functions to control the decode of commands received from first and second filing controllers 1 and 2 and data transfer and to cancel/reconstitute the construction of multiple writing. The respective filing devices 10, 20 and 30 respectively serially connect the first and second filing controllers 1 and 2 by file interface signal groups 101 and 102. Further, the respective filing devices 10, 20 and 30 are equipped with copy control circuits 12, 22 and 32 provided with processors and general interface control circuits and those circuits are serially connected.