A phenomenon pattern extraction unit extracts a phenomenon pattern of a past sensor signal of a facility. A related information correlation unit correlates the sensor signal based on maintenance history information. A phenomenon pattern classification reference creation unit creates a classification reference for classifying a phenomenon pattern based on the extracted phenomenon pattern and a work keyword included in the maintenance history information correlated with the sensor signal as the source of the phenomenon pattern. A phenomenon pattern classification unit classifies the phenomenon pattern based on the classification reference. A diagnosis model creation unit creates a diagnosis model for estimating a work keyword suggested to a maintenance worker based on the classified phenomenon pattern and the work keyword.