A device for controlling a color gamut includes: a color mapping module which converts a source image signal, based on a first color gamut look-up table; and a color gamut shift module which sets a second color gamut look-up table, based on a grayscale value determined corresponding to an external factor or user setting. When the color gamut shift module is enabled, the color mapping module converts the source image signal, based on the second color gamut look-up table.