receiving, first division information indicating whether to divide a current block into a plurality of sub-blocks from a bitstream, the first division information being related to sub-block-based intra prediction;

dividing, in response to the first division information indicating that the current block is divided into the plurality of sub-blocks, the current block into the plurality of sub-blocks; and

obtaining, based on an intra prediction mode of the current block, a prediction block of the current block by performing the sub-block-based intra prediction in units of the sub-blocks,

wherein, based on second division information signaled from the bitstream, the current block is divided into the plurality of sub-blocks in only one of a vertical direction or a horizontal direction,

wherein a number of the plurality of sub-blocks resulting from dividing the current block is adaptively determined based on whether a size of the current block is less than a threshold size pre-defined in a decoding apparatus,

wherein, in response to the size of the current block being less than the threshold size, the number of the sub-blocks is determined equal to 2,

wherein, in response to the size of the current block being greater than or equal to the threshold size, the number of the sub-blocks is determined equal to 4, and

wherein the threshold size is defined as 8×8.