A video decoding method performed by a decoding apparatus according to the present disclosure comprises the steps of: receiving a bitstream including information about merge data of a current block; checking mh intra flag information for mh intra prediction which is included in the information about the merge data; checking information about a merge triangle prediction on the basis of a checking result that a value of the mh intra flag information is related to checking the information about the merge triangle prediction included in the information about the merge data; deriving prediction samples for the current block on the basis of a result of checking the information about the merge triangle prediction; and generating a reconstructed picture on the basis of the prediction samples.