A gamut mapping apparatus and method using a vector stretching that increases lightness and chroma depending on the shape of a gamut under a consistent chromaticity of a color signal of a source device. The gamut mapping apparatus may include a first color space conversion block to convert an input color signal into a first color signal of a LCH color space; a vector stretching block to perform the gamut mapping and to output a second color signal; and a second color space conversion block to convert the second color signal into a color space of the input color signal. The gamut mapping may be carried out under the consistent chromaticity such that a frequency of discoloration decreases. Also, gamut mapping can be performed after the source and the target gamuts are calibrated such that adverse effects caused by geometrical characteristics of the gamut and a decrease in chroma are reduced.