A printing apparatus includes a reading unit to read a document image to generate image data, and a printing unit to print an image of the image data on a sheet supplied from any of multiple sheet storage portions. The printing apparatus determines whether an automatic selection function is enabled or disabled. The automatic selection function automatically selects, from among the sheet storage portions, a source for supplying a sheet that is used for printing. If the automatic selection function is enabled and a user specifies a predetermined sheet storage portion that has no sheet stored therein, the job execution instruction is not allowed. If the automatic selection function is disabled and a sheet storage portion that supplies a sheet for printing from among the plurality of sheet storage portions has no sheet stored therein, the job execution instruction is allowed.