A printing apparatus includes: a data receiver; a printing device; a tray; and a controller. The controller identifies, based on the received print data, a sheet size of a sheet to be used for printing and detects a sheet size of a sheet placed on the tray. A storage device stores an identified type associated with the identified sheet size and a detected type associated with the detected sheet size. When the identified type and the detected type are identical, the controller reduces or enlarges a size of an image based on the received print data, on the basis of the detected sheet size, and controls the printing device to conduct printing of the image. When the identified type and the detected type are different, the controller restricts conduct of the printing.