A main processor collects the edge information and color information of the pixels of a rendering target image using a rendering command, and sends the collected edge information and color information of the pixels to a sub-processor of the succeeding stage. The sub-processor sends the edge information and color information of a left rectangular region to a sub-processor, and also renders a right rectangular region and, upon receiving a process wait signal from the sub-processor, sends the rendering result to the sub-processor. The sub-processor renders the left rectangular region and sends the rendering result to the outside, and also sends, to the outside, the rendering result of the right rectangular region acquired by sending a process wait signal to the sub-processor.