A method of decoding an image, the method comprising: splitting a current picture into a plurality of maximum coding units, each coding unit having a maximum size according to information about a maximum size of the coding unit, wherein a maximum coding unit is split into a plurality of coding units using a depth information that denotes the number of times the coding unit is spatially split from the maximum coding unit; splitting a luminance component maximum coding unit and a chrominance component maximum coding unit of the current picture into one or more luminance component coding units and one or more chrominance component coding units, respectively according to split information; extracting a first intra prediction mode information that indicates an intra prediction mode applied to a luminance component prediction unit included in a luminance component coding unit; extracting a second intra prediction mode information that indicates an intra prediction mode applied to a chrominance component prediction unit corresponding to the luminance component predictionunit; and performing intra prediction on the luminance component prediction unit based on the first intra prediction mode information of the luminance component prediction unit and performing intra prediction on the chrominance component prediction unit based on the second intra prediction mode information, wherein the intra prediction mode indicates a particular direction among a plurality of directions, the particular direction being indicated by one of dx number in a horizontal direction and a fixed number in a vertical direction, and dy number in the vertical direction and a fixed number in the horizontal direction wherein dx number and dy number are one of value selected among; {32, 26, 21, 17, 13, 9, 5, 2, 0, -2, -5, -9, -13, -17, -21, -26} according to the particular direction, and wherein, when the second intra prediction mode information indicates that the intra prediction mode of the chrominance component prediction unit is equal to the intra prediction mode of the luminance component prediction unit, the intra prediction mode of the chrominance component prediction unit is determined to be equal to the intra prediction mode of the luminance component prediction unit. splitting a current picture into a plurality of maximum coding units, each coding unit having a maximum size according to information about a maximum size of the coding unit, wherein a maximum coding unit is split into a plurality of coding units using a depth information that denotes the number of times the coding unit is spatially split from the maximum coding unit; splitting a luminance component maximum coding unit and a chrominance component maximum coding unit of the current picture into one or more luminance component coding units and one or more chrominance component coding units, respectively according to split information; extracting a first intra prediction mode information that indicates an intra prediction mode applied to a luminance component prediction unit included in a luminance component coding unit; extracting a second intra prediction mode information that indicates an intra prediction mode applied to a chrominance component prediction unit corresponding to the luminance component predictionunit; and performing intra prediction on the luminance component prediction unit based on the first intra prediction mode information of the luminance component prediction unit and performing intra prediction on the chrominance component prediction unit based on the second intra prediction mode information, wherein the intra prediction mode indicates a particular direction among a plurality of directions, the particular direction being indicated by one of dx number in a horizontal direction and a fixed number in a vertical direction, and dy number in the vertical direction and a fixed number in the horizontal direction wherein dx number and dy number are one of value selected among; {32, 26, 21, 17, 13, 9, 5, 2, 0, -2, -5, -9, -13, -17, -21, -26} according to the particular direction, and wherein, when the second intra prediction mode information indicates that the intra prediction mode of the chrominance component prediction unit is equal to the intra prediction mode of the luminance component prediction unit, the intra prediction mode of the chrominance component prediction unit is determined to be equal to the intra prediction mode of the luminance component prediction unit.