A monitoring system, comprising: a monitored device; and a management device that communicates with the monitored device, wherein the monitored device comprises: a signal receiving means for receiving a signal including identification information for identifying a terminal existing within a prescribed range from the monitored device, as a received signal from the terminal; a terminal distance estimation means for, based on the received signal, estimating a distance from the monitored device to the terminal as terminal distance information; a terminal direction estimation means for, based on the received signal, estimating a direction directed from the monitored device to the terminal as terminal direction information; and a video capturing means for capturing a prescribed image-capturing range that is a neighborhood of the monitored device, the monitoring system being characterized in that: the management device comprises a data analysis means for analyzing a captured video that the video capturing means has captured to determine whether or not a prescribed event has occurred, and, in conjunction therewith, identifying the terminal distance information, the terminal direction information, and the identification information that are related to a capturing time of the captured video and based on the identified terminal distance information, terminal direction information, and identification information to determine a person who is likely a cause of the occurrence of a prescribed event among users of monitored devices which were attached to the management device when the prescribed event occurred. a monitored device; and a management device that communicates with the monitored device, wherein the monitored device comprises: a signal receiving means for receiving a signal including identification information for identifying a terminal existing within a prescribed range from the monitored device, as a received signal from the terminal; a terminal distance estimation means for, based on the received signal, estimating a distance from the monitored device to the terminal as terminal distance information; a terminal direction estimation means for, based on the received signal, estimating a direction directed from the monitored device to the terminal as terminal direction information; and a video capturing means for capturing a prescribed image-capturing range that is a neighborhood of the monitored device, a signal receiving means for receiving a signal including identification information for identifying a terminal existing within a prescribed range from the monitored device, as a received signal from the terminal; a terminal distance estimation means for, based on the received signal, estimating a distance from the monitored device to the terminal as terminal distance information; a terminal direction estimation means for, based on the received signal, estimating a direction directed from the monitored device to the terminal as terminal direction information; and a video capturing means for capturing a prescribed image-capturing range that is a neighborhood of the monitored device, the monitoring system being characterized in that: the management device comprises a data analysis means for analyzing a captured video that the video capturing means has captured to determine whether or not a prescribed event has occurred, and, in conjunction therewith, identifying the terminal distance information, the terminal direction information, and the identification information that are related to a capturing time of the captured video and based on the identified terminal distance information, terminal direction information, and identification information to determine a person who is likely a cause of the occurrence of a prescribed event among users of monitored devices which were attached to the management device when the prescribed event occurred.