A video decoding method performed by a decoding apparatus includes obtaining information regarding inter-prediction of a current block via a bitstream; forming an MVP candidate list based on neighbouring blocks of the current block; deriving costs with respect to MVP candidates that are included in the MVP candidate list; deriving a revised MVP candidate list based on the costs with respect to the MVP candidates; deriving MVP of the current block based on the revised MVP candidate list; deriving a motion vector of the current block based on the MVP and MVD of the current block; and performing prediction on the current block based on a reference picture index and the motion vector of the current block. The information regarding inter-prediction includes the reference picture index and the MVD.