Embodiments of the present specification provide a method and a device for processing a video signal for intra prediction. A method for decoding a video signal according an embodiment of the present disclosure includes: obtaining intra prediction information of a current block to which the intra prediction is applied, in which the intra prediction information includes a first flag indicating a predetermined first mode; determining an intra prediction mode of the current block based on the intra prediction information, wherein when the first flag corresponds to a first value, the first mode is determined as the intra prediction mode and when the first flag corresponds to a second value, one of a plurality of candidate modes is determined as the intra prediction mode; and generating a prediction sample of the current block based on the intra prediction mode and a reference sample in a current picture. A separate flag indicating whether to use a primarily used specific mode is used to reduce a data amount for transmission of the intra prediction mode and a processing time of information of the intra prediction.