A facility condition monitoring device includes an abnormality-degree-calculation-model construction part which constructs an abnormality-degree-calculation model for calculating an abnormality degree of a monitoring feature group of a monitoring target facility, based on a normal feature group extracted from a state-quantity fluctuation data of the monitoring target facility, an abnormality degree calculation part which calculates the abnormality degree of the monitoring feature group with the abnormality-degree-calculation model, an abnormality determination part which determines whether the monitoring target facility is abnormal, based on the abnormality degree, an abnormality-contribution-rate calculation part which obtains a contribution rate of each feature constituting the monitoring feature group used for calculating the abnormality degree determined as abnormal by the abnormality determination part, and an abnormality cause identification part which identifies an abnormality cause of the monitoring target facility, based on the contribution rate and a cause-and-effect matrix representing a relationship between the abnormality cause and the features.