A video signal processing method and device for encoding or decoding a video signal may perform operations of determining whether a coding tree block is divided into a plurality of blocks; determining whether an upper boundary of a current block is adjacent to an upper boundary of the coding tree block, determining a first intra prediction mode for prediction of the current block based on whether the upper boundary of the current block is adjacent to the upper boundary of the coding tree block, reconstructing the current block based on the first intra prediction mode.