Provided is a video decoding method including obtaining split information indicating whether a current block is to be split from a bitstream; splitting the current block into two or more sub-blocks when the split information indicates that the current block is to be split; determining lower horizontal coding order information of the sub-blocks of the current block according to higher horizontal coding order information applied to the current block, based on at least one of split information, size information, and neighboring block information of the current block; and decoding the sub-blocks according to the lower horizontal coding order information.