To prevent improper printing such as duplicate printing by eliminating the need for management up to the situation of toner adhesion thereby eliminating the need for canceling the printing.

The printer includes an output control unit which outputs the image data read from a storage unit by one or more data transfer control units, respectively, to a print unit designated beforehand among one or more print units, and a print control unit which designates the data transfer control unit to transfer the stored image data of one page to the output control unit when completion of storing image data of one page is notified from the data transfer control unit, and stops conveyance of a paper after printing on a paper, under printing in any one or more print units, is completed when a predetermined specific failure occurs.