It is an object to allow an advertising effect to be efficiently exercised by certainly printing an advertisement. For this purpose, according to the invention, print data of the user and advertisement data are synthesized so that an image based on the print data of the user is printed into a user print area on a recording medium and an image based on the advertisement data is printed into an advertisement print area on the recording medium, thereby forming image data. On the basis of the formed image data, the image based on the print data of the user is formed into the user print area on the recording medium and the image based on the advertisement data is formed into the advertisement print area on the recording medium.