This invention is targeted to realize preview displaying by using a system spooler. In the print system according to this invention, when an application program designates printing of a document, document data is spooled into EMF spool file 4. At the same time, previewer 3 is started to transmit a printing image generation request to print processor 5. The print processor 5 reads the data subjected to preview displaying out of the EMF spool file 4, have printer graphic driver 6 generate image data that has an appropriate display size, and informs the name of the image data file to the previewer 8, which then displays the image data.