A congestion control system provided in a connection portion between a network for an Internet provider and the Internet estimates a processing capability of a Web server on the basis of states of TCP/IP such as a window size of connection being connected, a cancellation rate of packet, a response time, a throughput and the like in a congestion state of the Web server to be requested and a network to the Web server and calculates a regulation duration for each Web server on the basis of the processing capability and the number of clients being in a waiting state for a re-request to the Web server so that the client is regulated when a response for regulating the re-request with the regulation duration is returned to the client. Consequently, since the number of re-requests per unit time can be made fixed, congestion due to re-requests can be prevented and the user can necessarily utilize the Web server upon re-request. Further, the service utilizable hour can be grasped to utilize the Web service deliberately.