PURPOSE: To prevent the step of the contour of a symbol displayed on a part of an image from being highlighted.

CONSTITUTION: Contour vector data specifying the contour of the symbol, contour color vector data specifying the color of the contour of the symbol and color vector data specifying the color of the symbol are stored in a font ROM 11 respectively. The contour vector data and the color vector data are read from the font ROE 11 and the contour color vector data is read from the font ROE 11 in accordance with the background image of the symbol so that the step of the contour of the symbol is not highlighted. The vector data read from the font ROE 11 is imparted to a memory 12 and image data corresponding to the vector data is obtained. A symbol video signal is generated from the image data and synthesized with an NTSC signal and imparted to a display device 15. Thus, the symbol is displayed on a part of the image displayed by the NTSC signal.