PURPOSE: To lighten the load on host data processing by informing the printer of the attribute of following data with attribute discrimination data at the head of print data.

CONSTITUTION: The attribute discrimination data are added at the head or a specific position of the print data 2 and those data are sent from a host computer 1 to a printer 4 or a printer branching device 5. The printer 4 decides what attribute the attribute discrimination data indicates by an attribute decision part and sorts respective data processing parts matching the attribute with a switcher to perform processes. The respective data processing parts process data so as to match the attribute with print parts, and the data are sent to an image processing part and printed out at a printing part after converted into dot data matching the printing mechanism and system of the printing part. The attribute decision part and switcher of the printer branching device 5 operate similarly to the printer 4 and the functions of the respective data processing part, image processing part, and printing part are realized by individual printers 13-15.