To provide a data communication system and method enabling reduction of user's burden by giving public relations information to transmit data to impose a communication charge on the public relations information providing end and enlargement public relations effect by extending a channel of public relations information among users as well.

In a transmitter/receiver 1, in transmitting or broadcasting data to a transmitter/receiver 2, access to a server 3 is gained to obtain public relations information, the public relations information is attached to the data and delivered to a network to be transmitted or broadcast to the transmitter/ receiver 2, the data to which public relations information is given is received by a relay device 6, and relayed to a data receiver. The quantity of data of given data of the public relations information received in this relay is managed, and accounting based on the quantity of data is performed for the public relations information providing end.