A color gamut conversion device includes: a target color coordinate converter configured to convert each RGB value of red (R), green (G), blue (B), cyan (C), magenta (M), yellow (Y), and white (W) of a target color coordinate into a tristimulus value XYZ; a reference conversion matrix generator configured to generate a first reference conversion matrix for converting each tristimulus value XYZ into an R′G′B′ value according to a color gamut of a reference display; a low power corrected value calculator configured to calculate a low power corrected value for correcting the R′G′B′ value; a lookup table (LUT) generator configured to generate an LUT including an R″G″B″ value corresponding to each RGB value by using a second reference conversion matrix that the low power corrected value is applied to the first reference conversion matrix; and a color gamut converter configured to convert image data of the RGB values into image data of the R″G″B″ values using the LUT.