To provide an abnormality monitoring device detecting fraudulent opening of a storage box and the like of an electric circuit.

A connecting member 30 connected to an external terminal of a monitoring unit 20 via a connector CNA is provided with a flexible sealing wire rod 31 winding around the circumference of a circuit storage box 91 and the like and a shortcircuit unit 32 having a shortcircuit circuit connected to the sealing wire rod 31 via the connector CNB and connecting between lines 311 and 314 in the sealing wire rod. The shortcircuit circuit is so formed as to connect the connector CNB by twisting and the shortcircuit circuit 32 is provided with a lock member fixing the winding part of the sealing wire rod 31. The sealing wire rod is provided with a single cable system including all the four lines in a core line and a two-cable system including two lines in cores respectively.