1. A server performance measurement method for operating a business application in at least one of a plurality of servers to measure performance of the server, comprising the steps of: a first step of transmitting information necessary for start or end of the measurement of performance of the server; a second step of extracting necessary information from a database on the basis of the information transmitted in the first step, preparing information for setting a load balancer that suitably distributes a load of the server and that is connected to the server in a mutually communicatable state, and transmitting these information to the server and the load balancer; a third step of extracting information that controls the load of the server and that contains a target load value of the server from a database on the basis of the information transmitted in the first step and starting the measurement of performance of the server; a fourth step of receiving feedback information transmitted from the server; a fifth step of comparing a load value of the server contained in the feedback information with the target load value of the server to decide whether the load of the server is varied or not, when the load of the server is varied, preparing feedback information rewriting information that contains policy for varying the load of the server to be transmitted, and when the load of the server is not varied, varying the target load value of the server and transmitting information concerning result of the measurement of performance of the server; a sixth step of rewriting the feedback information on the basis of the feedback information rewriting information and transmitting the rewritten feedback information to the load balancer; a seventh step of successively obtaining the information concerning the measurement result in the fifth step, judging end time of the measurement from the obtained information, and notifying the judgement; and an eighth step of relating the information concerning the measurement result in the fifth step to the business application operated in the server, and storing to manage in a database.