In this invention, a combined job obtained by combining a plurality of jobs is authenticated as a single job. According to the arrangement of this invention, when print jobs are to be spooled, these jobs are transferred from a dispatcher to a spooler where the jobs are combined. Upon reception of a print instruction, the print job is read out from a spool file, transferred from a despooler to a graphic engine again, and transferred from the dispatcher to a printer driver. At this time, the printer driver issues an authentication request in printing to a job accounting client. Thus, only one authentication request suffices for one combined job.