An image decoding method according to the present document may comprise the steps of: receiving flag information indicating whether or not matrix-based intra prediction (MIP) is to be used for a current block; receiving matrix-based intra prediction (MIP) mode information on the basis of the flag information; generating intra prediction samples for the current block on the basis of the MIP mode information; and generating reconstructed samples for the current block on the basis of the intra prediction samples, wherein a syntax element bin string for the MIP mode information is binarized by using a truncated binarization method.