The diagnosis device specifies a progression degree relating to a first information processing device for output information output by a first detection device at a first timing with respect to the first information processing device, based on device information indicates a progression degree that represents a degree to which the information processing device is abnormal with respect to the information processing device, determines whether or not information in which a first detection device identifier of the first detection device and the specified progression degree are associated with each other is included in progression-degree information in which a detection device identifier capable of identifying a detection device and the progression degree are associated with each other; and calculates the progression degree relating to the first information processing device according to the specified progression degree when the information is determined to be included in the progression-degree information.