A PAN is easily constructed by carrying out mutual authentication with a plurality of equipment in a home. A memory card is used to mutually authenticate any random equipment among a plurality of equipment set up at home, and a piece of desired communications equipment is chosen among a plurality of communicatable equipment exist in the communications range and is made communicable. Features of each equipment may be written in the memory card which can be distributed in advance. Before carrying out communications, the type of data, transmission rate, and other data can be established so that efficient transmission is enabled. In addition, the user can easily form a PAN. For example, even while traveling, the user can easily connects to a network the audio-visual equipment at a hotel in a destination.