A portable information terminal is placed in proximity with an ID recognition unit of a notebook PC. By reading ID from the portable information terminal, the notebook PC is able to identify a network address of the portable information terminal so as to establish a network connection with the portable information terminal. The notebook PC then sends suitable operation information to the portable information terminal via a network. For example, if presentation is running on the notebook PC, screen information for operating the presentation is transferred to the portable information terminal. Accordingly, by using one device connected to the other device by a wired or wireless network, the operation of the other device can be controlled.