A printer serving as an output destination can be automatically set from print data. Further, in order to search an optimum printer during a series of operations within a range from the issue of a print command to the printing and improve a working efficiency of the user, whether the data whose printing has been instructed by an application is a spool designated print job or not is discriminated (S1). When it is spool designated, a spooler interprets a DDI function, generates intermediate data, and spools as intermediate data into a spool file (S3). Whether all drawing functions outputted from the application have been spooled in the spool file or not is discriminated (S4). If YES, a print destination changing process is executed (S5). A print destination is changed and a network printer held in an RAM is updated. After that, the processing routine is returned to step S1 and the above processes are repeated.