The present invention reduces the influence of stuck processing having occurred in an overall data communication system. Data generated by a generation section of a first apparatus is transmitted by a transmission section to a second apparatus at a predetermined transmission rate. A processing section of the second apparatus processes the data received. A processing speed calculation section of the second apparatus calculates a processing speed at which the data is processed in the processing section. A notification section of the second apparatus notifies the first apparatus of the processing speed. A rate setting section of the first apparatus calculates a proper rate for transmitting the data to the second apparatus on the basis of a data processing speed in the second apparatus and performs setup so as to transmit the data to the second apparatus at the proper rate.