receiving a bitstream in which the image is encoded;

obtaining, from the bitstream, a single index for specifying a block division type of a current block in the image;

determining, based on the single index, the block division type of the current block from a candidate group pre-defined in the decoding apparatus,

wherein the single index is used to select one candidate division types among a plurality of candidate division types included in the candidate group,

wherein the plurality of candidate division types include a non-division, a first quad-division, a second quad-division, a binary-division and a triple-division,

wherein the first quad-division is representative of dividing, based on one horizontal line and one vertical line, one coding block into four coding blocks, the second quad-division is representative of dividing, based on three horizontal lines or three vertical lines, one coding block into four coding blocks, the binary-division is representative of dividing one coding block into two coding blocks, and the triple-division is representative of dividing one coding block into three coding blocks,

wherein the binary-division includes a horizontal binary-division and a vertical binary-division, and

wherein the bitstream includes a first flag specifying whether to perform the horizontal binary-division and a second flag specifying whether to perform the vertical binary-division, the first flag being different from the second flag;

dividing, based on the determined block division type, the current block into a plurality of sub-blocks; and

decoding each of the sub-blocks with reference to syntax information obtained from the bitstream; and

reconstructing the current block based on the decoded sub-blocks,

wherein the two coding blocks obtained by the binary-division have the same size each other, and

wherein a residual block for the sub-block is obtained by performing inverse quantization or inverse transformation.