A method for decoding an image according to the present invention comprises the steps of: receiving and decoding MPM index information for indicating an MPM candidate which is to be used as an intra prediction mode of a current block; generating an MPM candidate list containing a plurality of MPM candidates for the current block; determining the MPM candidate indicated by the decoded MPM index information as the intra prediction mode of the current block, among the plurality of the MPM candidates which constitute the MPM candidate list; and generating a prediction block corresponding to the current block by performing intra prediction for the current block based on the determined intra prediction mode.