In a system where a digital still camera 1101 is connected to a printer 1102 on a 1394 serial bus, when the digital still camera 1101 as a data transfer originator node transfers image data to the printer 1102 as a data transfer destination node, the printer 1102 sends information on the data processing capability of the printer 1102 to the digital still camera 1101 prior to data transfer. The digital still camera 1101 determines the block size of image data to be transferred in accordance with the data processing capability of the printer 1102, and sends image data of the block size to the printer 1102. The information indicates the capacity of a memory of the printer for storing print data, or the printing capability of a printer engine, i.e., printing resolution, printing speed and the like. Thus, data transfer is always efficiently performed regardless of the data processing capability of the printer 1102.