To reduce user's print operation instruction burden and to obtain an intended synthetic document for a unit number of copies in the case of outputting the synthetic document obtained by synthesizing plural independent document files for the unit number of desired copies.

Intermediate data of a document that is desired to be synthesized are respectively stored as a file in a hard disk drive 9 by operating a keyboard 5 and a pointing device 6 and when printing is requested to start, a printer driver respectively synthesizes the stored intermediate data on a RAM 3 at the time of the print instruction of the intermediate data of the temporarily stored document. Further, the temporarily stored intermediate data is synthesized and after synthesizing as the final intermediate data that can be outputted as one document, a printer converts the final intermediate data into analyzable print data and repeatedly outputs it for the unit number of designated copies.