An electronic-circuit fabricating system wherein an inspecting machine is provided for each of working machines such as a mask printing machine and an electronic-component mounting machine, to inspect a result of an operation of each working machine, and a monitoring device is arranged to receive information on monitoring-object portions of the working machines and information on the inspected result of the operation, to estimate the present state of each monitoring-object portion on the basis of these kinds of information, to obtain a tendency of change of the present state on the basis of the present state and stored past data, and to monitor the working machines so that the present state does not exceed a predetermined threshold state. When the present state of the monitoring-object portion has exceeded the thresholds state, the monitoring device estimates a cause for an abnormality of the working machine on the basis of the information on the working machine and the inspected result, and automatically compensates control data or activates a monitor or indicator to prompt the operator to implement a suitable treatment.