To make the top/bottom direction of a printing image to be printed on the front face of a printing medium coincide with the top/bottom direction of the print image to be printed on the rear face, without performing a coordinate conversion process to image data of an original image, when the original image of a double-sided original which is read by an original reversing image reader is perfected on the printing medium.

When a plate-making master corresponding to the original image on the front face of a double-sided original is mounted on a first printing drum 10, the first printing drum 10 is driven to rotate in a direction B1 which coincides with a rotating direction A1 during printing and at the same time, a second printing drum 20 is driven to rotate in a reverse direction B2 to a rotating direction A2 during printing, when a plate-making master corresponding to an original image on the rear face of the double-sided original is to be mounted on the second printing drum 20.