A method of encoding 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; performing intra prediction on a luminance component prediction unit and a chrominance component prediction unit; determining a first intra prediction mode information that indicates an intra prediction mode applied to the luminance component prediction unit included in a luminance component coding unit; determining a second intra prediction mode information that indicates an intra prediction mode applied to the chrominance component prediction unit corresponding to the luminance component prediction unit, the intra prediction mode applied to the chrominance component prediction unit being determined from among candidate intra prediction modes including the determined intra prediction mode applied to the luminance component prediction unit; and encoding the first intra prediction mode information and 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 dx number in a horizontal direction and dy number in the vertical direction, wherein dx number and dy number are integers, and wherein, when the intra prediction mode of the chrominance component prediction unit is equal to the intra prediction mode of the luminance component prediction unit, the second intra prediction mode information is set to indicate that the intra prediction mode of the chrominance component prediction unit is 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; performing intra prediction on a luminance component prediction unit and a chrominance component prediction unit; determining a first intra prediction mode information that indicates an intra prediction mode applied to the luminance component prediction unit included in a luminance component coding unit; determining a second intra prediction mode information that indicates an intra prediction mode applied to the chrominance component prediction unit corresponding to the luminance component prediction unit, the intra prediction mode applied to the chrominance component prediction unit being determined from among candidate intra prediction modes including the determined intra prediction mode applied to the luminance component prediction unit; and encoding the first intra prediction mode information and 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 dx number in a horizontal direction and dy number in the vertical direction, wherein dx number and dy number are integers, and wherein, when the intra prediction mode of the chrominance component prediction unit is equal to the intra prediction mode of the luminance component prediction unit, the second intra prediction mode information is set to indicate that the intra prediction mode of the chrominance component prediction unit is equal to the intra prediction mode of the luminance component prediction unit.