To attempt to shorten a rewriting time considerably by minimizing labor and loading programs for controlling all terminal station control units 5 simultaneously.

In the system, by using a simultaneous instruction function from a control station, which is one of the important functions of, for example, a disaster prevention administrative communication network system, to a terminal station, a mode of simultaneous instruction is provided with a condition confirmation mode of a terminal station control unit 5, a program loading mode for instructing the control unit 5 control operation to the terminal control unit 5, a program writing mode, a restarting mode, and a program transferring mode.