A printing system includes a data processing terminal and a printer. When the printer receives a print request of print target data from the data processing terminal, a data processing unit of the printer develops the print target data into print data in the bitmap format by page, concurrently with the creation of thumbnails by page. When the data processing unit requests the printer to deliver a print progress monitoring page, the printer displays a thumbnail of a printed page of the print job being currently processed, via a Web server. In addition, the Web server creates a data file, in which a command for automatically refreshing a Web browser is written, that is delivered to the data processing terminal.