The condition of each of machines on dispersed lines can be quantitatively grasped before an error occurs, without going to the machine installation site, so that the efficiency of machine fault diagnosis can be improved. One server terminal for diagnosis is provided for each factory at the use side. As clients for this server terminal, a press controller, a workpiece conveyor control motion controller, and a line production management computer are connected through an Ethernet. The server terminal is connected via modem and telephone line to a diagnosis terminal with a modem which is installed at the maker side. The operating condition of a press is measured and recorded as continuous time-series waveform data, using an analog input card. The recorded waveform data is processed to be graphically displayed on the diagnosis terminal, etc.