Monitoring device and monitoring method thereof, monitoring system, and recording medium in which computer program is stored

The present invention provides a monitoring device, etc., with which, even for a system in which a plurality of objects to be monitored are complicatedly associated, it is possible to have a high capability of detecting a state pertaining to the system and to reduce erroneous detection. A monitoring device 1 is provided with a first model generation unit 2 for dividing second time-series information, among first time-series information pertaining to an object to be monitored, that is correlated to each item, and generating a model pertaining to the divided time-series information, and a determination unit 3 for finding whether correlation is maintained or not by applying third time-series information to the model, and making a determination pertaining to each item on the basis of the result of the finding.