To provide an equipment monitoring device for incorporating equipment not connected to a network other than information communication equipment to an SNMP environment.

This equipment monitoring device 4 is provided with a network 6, a communication processing circuit 41 for communicating with the manager 21 of a host computer 2, a message processing circuit 42 for processing messages transmitted and received in the communication processing circuit 41, a monitoring processing circuit 43 for cyclically generating monitoring messages in the operation state of monitoring object equipment 3, a timer circuit 44 for cyclically activating the monitoring processing circuit 43, a signal detection circuit 45 for connecting a signal line for indicating the operation state of the monitoring object equipment 3 and detecting the operation state, a monitoring cycle setting circuit 46 for setting a cycle to the timer circuit 44, a monitoring amount setting circuit 47 for setting the threshold of a signal detection level to the signal detection circuit 45, a setting input circuit 48 for inputting setting values to the monitoring cycle setting circuit 46 and the monitoring amount setting circuit 47 and a nonstop power source 49.