A symbol cache checking part for checking to see whether or not an image of a symbol of the same type as a symbol to be drawn is written in a texture. When the symbol cache checking part determines that an image of a symbol of the same type as the symbol to be drawn is written in a texture, a texture coordinate setting part sets the write position of the above-mentioned symbol in the texture to the vertices of a 3D polygon generated by a polygon generating part as texture coordinates, and a polygon drawing unit 40 draws this 3D polygon.