Monitoring system

Abstract

Provided is a monitoring system that makes it possible to make the replacement of a sensor mounted to an object to be monitored less frequent. One example of a monitoring system of the present invention includes: a vibration string sensor (8) that is mounted to an object to be monitored, the object including a water pipeline or a bridge, and that outputs, when a vibration string (8g) built in the vibration string sensor (8) is vibrated freely, an electrical signal corresponding to vibration of the vibration string (8g); and a determiner (34b) that determines a state of the object to be monitored based on a peak frequency within a second frequency range that does not include a first frequency range including a natural frequency of the vibration string (8g), the peak frequency being obtained by performing frequency analysis on measurement data of the electrical signal outputted from the vibration string sensor (8).