A rendering display device, comprising: a monitor, a plurality of non-display memories (301, 302, 303) for storing image data (101, 102, 103) for a plurality of images; a layout information storage unit (501, 502, 503) for storing layout information that specify display areas for the plurality of images on the monitor and specify, in case of overlapping images, front-back relationships thereamong; a plurality of entire-image non-display memories (31, 32) for storing based on the layout information image data (101, 102, 103) transferred from at least one of the non-display memories (301, 302, 303) to one of the entire-image non-display memories (31, 32); a transfer control unit for transferring to one of the entire-image non-display memories image data (101, 102, 103) stored in at least one of the non-display memories (301, 302, 303); a plurality of display buffers (11, 12) for storing image data (101, 102, 103) for images transferred from each of the entire-image non-display memories (31, 32) to one of the display buffers (11, 12) to be displayed on the monitor; characterized in that the rendering display device further comprises a layer control unit for informing the transfer control unit of transfer information that specify to which entire-image non-display memory (31, 32), image data (101, 102, 103) stored in the each of non-display memories (301, 302, 303) is transferred; a plurality of update information recording units (401, 402, 403) for storing update information of the image data (101, 102, 103); an update information control unit for receiving the update information and informing the transfer control unit of the update information; and in case of an update of image data (101, 102, 103) stored in one of the non-display memories (301, 302, 303), the transfer control unit receives the update information and transfers only image data (101, 102, 103), that are specified by the transfer information to be transferred from another one of the non-display memories (301, 302, 303) to the same entire-image non-display memory as the updated image data (101, 102, 103) and specified by the layout information to be displayed in front of the updated image data (101, 102, 103), to one of the entire-image non-display memories (31, 32) specified by the transfer information with the updated image data (101, 102, 103). a monitor, a plurality of non-display memories (301, 302, 303) for storing image data (101, 102, 103) for a plurality of images; a layout information storage unit (501, 502, 503) for storing layout information that specify display areas for the plurality of images on the monitor and specify, in case of overlapping images, front-back relationships thereamong; a plurality of entire-image non-display memories (31, 32) for storing based on the layout information image data (101, 102, 103) transferred from at least one of the non-display memories (301, 302, 303) to one of the entire-image non-display memories (31, 32); a transfer control unit for transferring to one of the entire-image non-display memories image data (101, 102, 103) stored in at least one of the non-display memories (301, 302, 303); a plurality of display buffers (11, 12) for storing image data (101, 102, 103) for images transferred from each of the entire-image non-display memories (31, 32) to one of the display buffers (11, 12) to be displayed on the monitor; characterized in that the rendering display device further comprises a layer control unit for informing the transfer control unit of transfer information that specify to which entire-image non-display memory (31, 32), image data (101, 102, 103) stored in the each of non-display memories (301, 302, 303) is transferred; a plurality of update information recording units (401, 402, 403) for storing update information of the image data (101, 102, 103); an update information control unit for receiving the update information and informing the transfer control unit of the update information; and in case of an update of image data (101, 102, 103) stored in one of the non-display memories (301, 302, 303), the transfer control unit receives the update information and transfers only image data (101, 102, 103), that are specified by the transfer information to be transferred from another one of the non-display memories (301, 302, 303) to the same entire-image non-display memory as the updated image data (101, 102, 103) and specified by the layout information to be displayed in front of the updated image data (101, 102, 103), to one of the entire-image non-display memories (31, 32) specified by the transfer information with the updated image data (101, 102, 103).