A method of decoding an image, the method comprising: extracting split information for a coding unit of a depth k, where k is integer, the split information indicating whether to split the coding unit of the depth k, where k is integer, into four equal-sized, square-shaped coding units of a depth, k+1, from a bitstream including encoded data of the image encoded based on square-shaped maximum coding units hierarchically split into deeper square-shaped coding units as a depth deepens; determining a split structure of a square-shaped maximum coding unit, according to the split information; extracting, when the square-shaped maximum coding unit is split up to a current coding unit which is no longer split according to the split information, skip information indicating whether a prediction mode of the current coding unit is a skip mode, from the bitstream; when the skip information indicates that the prediction mode of the current coding unit is the skip mode, determining the current coding unit as one prediction unit of which prediction mode is the skip mode; and when the skip information indicates that the prediction mode of the current coding unit is not the skip mode, obtaining one or more prediction units from the current coding unit by equally splitting a width or a height of the current coding unit by two, or by equally splitting both the height and the width of the current coding unit by two, or by determining the current coding unit as the one or more prediction units based on a partition type of the current coding unit, the one or more prediction units being used for prediction decoding of the current coding unit and the partition type being obtained from the bitstream, wherein, a picture is split into a plurality of square-shaped maximum coding units according to information about maximum size of a coding unit, when a size of the current coding unit is 2Nx2N, where N is integer, and the prediction mode of the current coding unit is the skip mode, a size of the one prediction unit is 2Nx2N, the split information for the coding unit of the depth k has a value of zero or one, when the split information for the coding unit of the depth k has a value of zero, the split information indicates not to split the coding unit of the depth k, when the split information has a value of one, the split information indicates to split the coding unit of the depth k, the skip information is a flag having a value of zero or one, and when the skip information has a value of one, the skip information indicates that the prediction mode of the current coding unit is the skip mode. extracting split information for a coding unit of a depth k, where k is integer, the split information indicating whether to split the coding unit of the depth k, where k is integer, into four equal-sized, square-shaped coding units of a depth, k+1, from a bitstream including encoded data of the image encoded based on square-shaped maximum coding units hierarchically split into deeper square-shaped coding units as a depth deepens; determining a split structure of a square-shaped maximum coding unit, according to the split information; extracting, when the square-shaped maximum coding unit is split up to a current coding unit which is no longer split according to the split information, skip information indicating whether a prediction mode of the current coding unit is a skip mode, from the bitstream; when the skip information indicates that the prediction mode of the current coding unit is the skip mode, determining the current coding unit as one prediction unit of which prediction mode is the skip mode; and when the skip information indicates that the prediction mode of the current coding unit is not the skip mode, obtaining one or more prediction units from the current coding unit by equally splitting a width or a height of the current coding unit by two, or by equally splitting both the height and the width of the current coding unit by two, or by determining the current coding unit as the one or more prediction units based on a partition type of the current coding unit, the one or more prediction units being used for prediction decoding of the current coding unit and the partition type being obtained from the bitstream, wherein, a picture is split into a plurality of square-shaped maximum coding units according to information about maximum size of a coding unit, when a size of the current coding unit is 2Nx2N, where N is integer, and the prediction mode of the current coding unit is the skip mode, a size of the one prediction unit is 2Nx2N, the split information for the coding unit of the depth k has a value of zero or one, when the split information for the coding unit of the depth k has a value of zero, the split information indicates not to split the coding unit of the depth k, when the split information has a value of one, the split information indicates to split the coding unit of the depth k, the skip information is a flag having a value of zero or one, and when the skip information has a value of one, the skip information indicates that the prediction mode of the current coding unit is the skip mode.