Even if a look-up service cannot be searched, services of a service provider can be used while consumption of resources is suppressed. A client issues a multi cast notification if the look-up service cannot be searched. In response to the multi cast notification, the service provider issues a service register request (transmission of a service object) to the transmission originating client. The client temporarily stores the received service object in a memory. A service object not coincident with the attribute information of a desired service is deleted from the memory, and the desired service is used by using an agent object coincident with the attribute information of the desired service. A service search request from another client responding to the multi cast notification is rejected.