An image encoding apparatus comprising: a processor configured to: generate information about a maximum coding unit, used to split an image into a plurality of square maximum coding units, generate information about coding units, having different sizes according to depths included in the maximum coding unit, used to hierarchically split a maximum coding unit, among the plurality of maximum coding units, into square coding units; perform intra prediction or inter prediction on at least one prediction unit to generate a predictor; and generate transform coefficients based on the predictor and the image, wherein: the maximum coding unit is hierarchically split into the coding units including a coding unit of a current depth and a coding unit of a depth greater than the current depth, the coding unit of the current depth is split into four coding units of the depth greater than the current depth, independently from neighboring coding units of the current depth, and the coding unit of the depth greater than the current depth is predicted using the at least one prediction unit and is transformed using 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 depth greater than the coding unit of the current depth, and characterised in that the encoding apparatus is configured to support a transformation unit, among the at least one transformation unit, having a size of 2Nx2N that includes four prediction units having a size of NxN. generate information about a maximum coding unit, used to split an image into a plurality of square maximum coding units, generate information about coding units, having different sizes according to depths included in the maximum coding unit, used to hierarchically split a maximum coding unit, among the plurality of maximum coding units, into square coding units; perform intra prediction or inter prediction on at least one prediction unit to generate a predictor; and generate transform coefficients based on the predictor and the image, wherein: the maximum coding unit is hierarchically split into the coding units including a coding unit of a current depth and a coding unit of a depth greater than the current depth, the coding unit of the current depth is split into four coding units of the depth greater than the current depth, independently from neighboring coding units of the current depth, and the coding unit of the depth greater than the current depth is predicted using the at least one prediction unit and is transformed using 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 depth greater than the coding unit of the current depth, and characterised in that the encoding apparatus is configured to support a transformation unit, among the at least one transformation unit, having a size of 2Nx2N that includes four prediction units having a size of NxN. the maximum coding unit is hierarchically split into the coding units including a coding unit of a current depth and a coding unit of a depth greater than the current depth, the coding unit of the current depth is split into four coding units of the depth greater than the current depth, independently from neighboring coding units of the current depth, and the coding unit of the depth greater than the current depth is predicted using the at least one prediction unit and is transformed using 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 depth greater than the coding unit of the current depth, and characterised in that the encoding apparatus is configured to support a transformation unit, among the at least one transformation unit, having a size of 2Nx2N that includes four prediction units having a size of NxN.