A decentralized system managing method is provided for adapting a decentralized service changing day by day without having to recreate the overall existing application and for optimally executing the application without having to burden the overhead of the network load. The managing method is arranged to obtain the log information in executing the program, accumulate and work the log information, and present the result to the user. At a time, the managing method is served to create and issue an improving instruction for making the application execution the most approximate according to the optimization rule instructed by the user.