A conversion unit converts a command part of an image inclusion command into an internal command. A first memory unit stores an image non-inclusion command and the internal command converted by the conversion unit. A second memory unit stores an image data part of the image inclusion command. A restart page number memory unit stores restart page number information when a print process being executed is interrupted in order to execute an interruption print process. When restarting the interrupted print process, a control unit executes control to read out the internal command and the image non-inclusion command stored in the first memory unit up to the page indicated by the restart page number information, and from the page indicated by the restart page number, further executes control to read out from the second memory unit the image data part following the internal command read out from the first memory unit.