A method and apparatus for compensating for the luminance of a color signal. The luminance compensation method includes obtaining an allowable luminance ratio of a color signal, obtaining a luminance enhancing ratio of a color signal using the allowable luminance ratio, and compensating for the luminance of the color signal using the luminance enhancing ratio. The luminance ratio is the ratio of a luminance according to saturation when a color signal is represented by four or more multiple primary colors, to a luminance according to saturation when the color signal is represented by three colors.