Upon receiving a notification from a device that a content configuration changed, a management apparatus that manages one or more devices searches among contents possessed by the device in question for a content for which first identification information recorded in a second area and in a first area of attendant information of the content differ, and determines whether second identification information recorded in a second area of the attendant information of the retrieved content is unique among all contents in the system. When the management apparatus determines that second identification information of the attendant information is not unique, it updates the first identification information recorded in the second area of the attendant information with first identification information recorded in the first area of the attendant information and updates the second identification information with identification information that is unique in the system, to thereby update the attendant information of the content.