An image decoding method, the method comprising: decoding flag information indicating whether one of intra-prediction modes of a most probable mode of the current block and the intra-prediction mode of the current block are identical; and when the decoded flag information indicates that one of the intra prediction modes of the MPM and the intra-prediction mode of the current block are identical, deriving the intra-prediction mode of the current block by decoding a syntax element including information regarding the intra-prediction modes of the MPM (mpm_idx); when the decoded flag information indicates that the intra-prediction modes of the MPM and the intra-prediction mode of the current block are not identical, deriving the intra-prediction mode of the current block by decoding a syntax element including information regarding remaining intra prediction modes(rem_intra_luma_pred_mode); and generating a prediction block of the current block based on the intra-prediction mode of the current block, characterized in that said deriving the intra-prediction mode of the current block is performed based on a table including intra-prediction mode information, the table is a table mapping intra-prediction modes and code number information of the intra-prediction modes, and, in the table, when an intra-prediction mode is a planar mode, the intra-prediction mode is mapped to a code number 0, when an intra-prediction mode is a DC mode, the intra-prediction mode is mapped to a code number 1, and when intra-prediction modes are directional intra-prediction modes, the intra-prediction modes are mapped to code numbers 2 to 34 according to directivity of the intra-prediction modes, wherein the intra-prediction modes of the MPM are three different intra-prediction modes derived based on intra-prediction modes derived based on neighbour blocks of the current block and an additional intra-prediction mode, wherein the syntax element including information regarding remaining intra prediction modes (rem_intra_luma pred mode) is a value coded using fixed 5 bits. decoding flag information indicating whether one of intra-prediction modes of a most probable mode of the current block and the intra-prediction mode of the current block are identical; and when the decoded flag information indicates that one of the intra prediction modes of the MPM and the intra-prediction mode of the current block are identical, deriving the intra-prediction mode of the current block by decoding a syntax element including information regarding the intra-prediction modes of the MPM (mpm_idx); when the decoded flag information indicates that the intra-prediction modes of the MPM and the intra-prediction mode of the current block are not identical, deriving the intra-prediction mode of the current block by decoding a syntax element including information regarding remaining intra prediction modes(rem_intra_luma_pred_mode); and generating a prediction block of the current block based on the intra-prediction mode of the current block, characterized in that said deriving the intra-prediction mode of the current block is performed based on a table including intra-prediction mode information, the table is a table mapping intra-prediction modes and code number information of the intra-prediction modes, and, in the table, when an intra-prediction mode is a planar mode, the intra-prediction mode is mapped to a code number 0, when an intra-prediction mode is a DC mode, the intra-prediction mode is mapped to a code number 1, and when intra-prediction modes are directional intra-prediction modes, the intra-prediction modes are mapped to code numbers 2 to 34 according to directivity of the intra-prediction modes, wherein the intra-prediction modes of the MPM are three different intra-prediction modes derived based on intra-prediction modes derived based on neighbour blocks of the current block and an additional intra-prediction mode, wherein the syntax element including information regarding remaining intra prediction modes (rem_intra_luma pred mode) is a value coded using fixed 5 bits.