A printing system is provided with a dummy data insertion unit configured to insert dummy data into print data based on waiting time occurring when post-processing is performed by a post-processing device (for example, a collating machine). In a printing unit, a dummy page is printed on the basis of the dummy data. A dummy page removing unit configured to remove a dummy page from printed printing paper so that the dummy page is not supplied to the post-processing device is provided between the printing device and the post-processing device.