An image encoding/decoding method and device are provided. An image decoding method according to the present invention can comprise the steps of: restoring an MFM indicator for indicating whether an intra prediction mode of a current block is a predetermined intra prediction mode; deriving the intra prediction mode of the current block on the basis of the MFM indicator; and generating, on the basis of the intra prediction mode, a prediction block of the current block by performing intra prediction on the current block.