PURPOSE: To promptly perform the pursuit of a fault cause by enabling other fault processings on a slave station side while the fault processing is performed on a main station side even when plural different faults occur in the same time zone, in the fault processing of a data communication network monitor and control system.

CONSTITUTION: A file control means AN reads fault message data from the fault message file within a magnetic disk device 6 and expands the data to each table for a main station MS and for a slave station WSN on a storage device 13. A message analysis means CN transmits a message to be transmitted from a packet exchange to the main station and performs the color change of a processor state on a comprehensive monitor screen of a display device 7 of the main station and slave station when the message exists in each fault message table in the storage device 13. Thus, an automatic issue command corresponding to a fault message for a processor selected by a command to be transmitted from an input means 5 or the main station is read from each command table and is transmitted to a packet exchange.