The resources kept by a number of entities are made available mutually by each of the entities. A user using a user terminal requests a resource, to be provided by a resource providing server, to a window server through a communication line. A user information database records information for authenticating the user. A resource provider database records information for verifying a reliability of a resource provider. A resource provider information database records information for verifying the window server. 13 user information database records information of a user authenticated by the window server to allow the access to a resource. A permission data database records information for restricting the access to a resource.