In a print system comprising a first printing unit for printing images on a first surface of a continuous sheet, a reading unit for reading an image, and a second printing unit for printing images on a second surface of the continuous sheet, in the case where the first printing unit prints a control image irregularly inserted between the images based on image data on the first surface of the continuous sheet, the first printing unit prints an identification mark which enables the control image to be identified on the first surface of the continuous sheet, and in the case where the reading unit reads an identification mark printed on the first surface of the continuous sheet, the second printing unit is caused not to print images based on image data in an area corresponding to the control image on the continuous sheet.