A method for decoding an image, according to the present invention, can comprise the steps of: drawing out a vector predictor of a block vector for indicating a reference block with respect to a current block to be predicted within a current picture; drawing out the block vector on the basis of the vector predictor and a vector differential value corresponding to a different value of the block vector and the vector predictor; and generating a prediction block with respect to the current block on the basis of the block vector.