A first feature quantity computing unit that computes a first feature quantity representing an average of a plurality of driving loads recorded by a driving load of a fixing section recording unit of an image forming device that records the driving load acquired by a driving load acquiring unit that acquires the driving load, a second feature quantity computing unit that computes a second feature quantity representing a deviation of the plurality of the driving loads, and a diagnosis unit that performs failure diagnosis including estimation of a cause of a failure of the fixing section using the first feature quantity and the second feature quantity are used.