To make it possible to call a suitable monitor in turn out of a plurality of monitors in accordance with nearness to an abnormal position and the sort of required processing.

Data of a monitored target are collected, the data are managed by a monitor and control means, and when abnormality is generated, the monitor and control means generates alarms to a plurality of portable monitor terminals in previously determined order. In the case of determining the alarm order by places, an area to be monitored is divided into some ranges, alarms are installed in respective ranges, and when abnormality is generated, the monitor and control means calculates differences of coordinates from the installation place of the alarm generating the abnormality and a monitors' positions and generates alarms in the ascending order of differences. In the case of determining the alarm order by ability, necessary ability of abnormality processing is classified in each alarm, a level of importance is set in each class, classification and levels of the monitors also are determined, and when a certain alarm is activated, the ability and level required for the alarm and that of monitors are compared with each other and monitors are called in turn from the monitor whose ability and level are closest to the ability and level required for the alarm.