In a printing system in which a data processing apparatus and a plurality of print processing apparatuses can communicate via a communication medium, document data and print instruction data for each printer are transmitted from the data processing apparatus to a plurality of print processing apparatuses by a multicasting protocol. Thus, a print job is transmitted to a plurality of print processing apparatuses without enhancing a traffic on a network and the print job can be efficiently processed in parallel by a plurality of print processing apparatuses.