An image output apparatus 1 performs output processes of a plurality of kinds of image data in different forms or states in accordance with the forms of the image data, and includes an image storage unit 100 for storing or saving the image data having undergone the output processes by sorting the image data in accordance with the forms thereof. Since the image data having once undergone the output processes are stored or saved in the image storage unit 100, if there is a need to output again the image data having once undergone an output process for the reason that the first output process has failed or the number of copies printed in the first output process has been insufficient, the same image data need not be input again, and thus, the load on the apparatus can be reduced and the image data can be output again in a short time.