An information service system comprises a portable unit carried by the user and an identification tag for supplying information on the present position of the user or the place where the user is approaching. The identification tag transmits the transmission information including the specified information stored in advance using infrared light or the like. The portable unit that has entered a predetermined range of the identification tag, upon receipt of the transmission information, demodulates the specified information and outputs the specified information from an information output unit such as a speaker. By the way, in the case where the specified information is an identification tag ID for specifying the particular identification tag, the portable unit selects the guide information corresponding to the identification tag ID through the portable unit controller and outputs it from the information output unit.