A spool file modifying device employed in a print server is connected with a printer. Further, the print server and at least one external terminal are interconnected. A spool file representing a print job that is instructed at the external terminal is converted into print data adaptable to the printer. The spool file modifying device includes a font data extracting system that extracts font data included in the spool file, a registering system that registers the extracted font data with the print server, and a modifying system that modifies the spool file to create a modified spool file in accordance with modifying information included in the spool file. The modified spool file is converted into the print data using the extracted font data, and then transmitted to the printer.