A graphics decoder which stores color number data of each pixel of the display screen (33), which is acquired from a subcode signal, sequentially reads out the color number data to produce a graphics RGB signal referring to a color look-up table, and supplies the graphics RGB signal to a CRT display (33). When a graphics command acquired from the subcode signal is a screen-scroll command, scroll data is obtained from pointer data included in that scroll command, and that scroll data is output at a timing synchronous with a horizontal sync signal or vertical sync signal to set the read address of the display memory. When the graphics command is a color look-up table write command, the color look-up table is updated at a timing synchronous with the first horizontal sync signal or vertical sync signal after the generation of that write command.