A managing method of an image forming system having at least one image forming apparatus including a first image forming apparatus, and a plurality of servers including a first server and managing the first image forming apparatus, the managing method includes determining whether the first server operates normally, requesting the plurality of server except the first server to manage the first image forming apparatus, if the first server operates abnormally, and allowing a second server among the plurality of servers except the first server to manage the first image forming apparatus in response to the request.