An image decoding method comprising: receiving information about a maximum size of a coding unit; dividing an image into a plurality of square maximum coding units using the information about the maximum size of the coding unit; determining the coding unit within a hierarchical structure of a maximum coding unit, among the plurality of maximum coding units using information about coding units parsed from a bitstream; parsing, from the bitstream, quantized transformation coefficients of at least one transformation unit in the coding unit; inverse quantizing the quantized transformation coefficients to generate transformation coefficients of the at least one transformation unit; and inverse transforming the transformation coefficients to generate residual components of the at least one transformation unit, wherein, the maximum coding unit is hierarchically split into one or more square coding units of depth including at least one of a coding unit of a current depth and a coding unit of a depth greater than the current depth, a coding unit of the current depth is split into four square coding units of a depth greater than the current depth, independently from neighboring coding units of the current depth, and a coding unit of the depth greater than the current depth is predicted using at least one prediction unit and is inverse-transformed using the at least one transformation unit, wherein the at least one prediction unit is one among blocks including: a block equal in size to the coding unit of the depth greater than the current depth; and a block among a plurality of blocks generated by equally dividing at least one of height and width of the coding unit of the depth greater than the current depth, wherein the at least one transformation unit is one among blocks including: a block equal in size to the coding unit of the depth greater than the current depth; and a block among a plurality of blocks generated by equally dividing height and width of the coding unit of the depth greater than the current depth, and characterised in that the decoding method supports a transformation unit, among the at least one transformation unit having a size of 2N x 2N that includes four prediction units among the at least one prediction unit having a size of N x N. receiving information about a maximum size of a coding unit; dividing an image into a plurality of square maximum coding units using the information about the maximum size of the coding unit; determining the coding unit within a hierarchical structure of a maximum coding unit, among the plurality of maximum coding units using information about coding units parsed from a bitstream; parsing, from the bitstream, quantized transformation coefficients of at least one transformation unit in the coding unit; inverse quantizing the quantized transformation coefficients to generate transformation coefficients of the at least one transformation unit; and inverse transforming the transformation coefficients to generate residual components of the at least one transformation unit, wherein, the maximum coding unit is hierarchically split into one or more square coding units of depth including at least one of a coding unit of a current depth and a coding unit of a depth greater than the current depth, a coding unit of the current depth is split into four square coding units of a depth greater than the current depth, independently from neighboring coding units of the current depth, and a coding unit of the depth greater than the current depth is predicted using at least one prediction unit and is inverse-transformed using the at least one transformation unit, wherein the at least one prediction unit is one among blocks including: a block equal in size to the coding unit of the depth greater than the current depth; and a block among a plurality of blocks generated by equally dividing at least one of height and width of the coding unit of the depth greater than the current depth, wherein the at least one transformation unit is one among blocks including: a block equal in size to the coding unit of the depth greater than the current depth; and a block among a plurality of blocks generated by equally dividing height and width of the coding unit of the depth greater than the current depth, and characterised in that the decoding method supports a transformation unit, among the at least one transformation unit having a size of 2N x 2N that includes four prediction units among the at least one prediction unit having a size of N x N.