A session management system enabling network resources to be efficiently utilized or saved when communication addresses are assigned to a network interface. The system manages sessions between a server having a plurality of addresses and a client. It is determined, in a case where an application provided with the client requests to communicate with the server, whether or not a session in which an address different from an address designated by the application is used is already established between the client and the server. The application is caused to communicate with the server by using the already established session when it is determined that the session is already established, and communicate with the server by using a newly established session when it is determined that the session is not established.