Provided are a method and a device for decoding a video signal. The method may include determining an intra prediction mode of a current block, performing intra prediction of current block based on the intra prediction mode and the reference sample, wherein when the intra prediction mode of the second coding block has a vertical direction, prediction samples resultant from the intra prediction are corrected by using different information of neighboring samples, and the correction is applied to a plurality of columns of the second coding block.