Abstract: Provided are: a data related information generating unit for generating data related information DL including detection data and air conditioner information of air conditioners; a class classifying unit for creating a plurality of classes on the basis of the air conditioner information related to alarm data extracted by an alarm data extracting unit among the air conditioner information and for classifying the data related information DL into the plurality of classes; a priority setting unit for setting priority to each of a plurality of types of alarm data and the plurality of classes; and a priority calculating unit for assessing co-occurrence of anomaly data extracted by an anomaly data extracting unit and the alarm data, assessing co-occurrence of the alarm data and the plurality of classes, assigning priority about the alarm data and the plurality of classes to the co-occurred anomaly data, and calculating priority of anomaly data.