<p>An image forming apparatus has an upper print head unit and a lower print head unit that print plural printing areas in order on a printing medium. The image forming apparatus defers printing, as long as the image data corresponding to the areas to be printed are not transferred from a host apparatus, and begins printing when the image data are transferred from the host apparatus. The image forming apparatus can thus print an unfixed length of continuous image without monopolizing the host apparatus. <IMAGE></p>
