A method of decoding a video, the method comprising: extracting, from a bitstream, information about a maximum size of a coding unit, information about a maximum depth indicating a total number of possible times a maximum coding unit is split, and split information indicating whether a coding unit of a current depth is split into coding units of a lower depth; determining a plurality of maximum coding units by dividing a picture using the information about a maximum size of the coding unit; determining, based on the split information, coding units of a hierarchical structure comprising coding units which are not split any more among coding units split from each maximum coding unit among the plurality of maximum coding units; and decoding the coding units of the hierarchical structure in the each maximum coding unit, wherein: the each maximum coding unit is hierarchically split into coding units of depths including at least one of a current depth and a lower depth according to the split information, a minimum coding unit among the coding units is determined by splitting the each maximum coding unit by the maximum depth, and when the a size of the coding unit (900, 930, 960) of the current depth is greater than a size of the minimum coding unit, the split information is obtained for the coding unit of the current depth from the bitstream, when the split information indicates a split for the coding unit of the current depth, the coding unit of a current depth is split into coding units of the lower depth by dividing a height and width of the coding unit of a current depth by two, and when the split information indicates a non-split for the coding unit of the current depth, a plurality of prediction units are determined in the coding unit of the current depth and inter prediction is performed on the plurality of prediction units, a transformation unit is determined from the coding unit of the current depth and inverse transformation is performed on the transformation unit. extracting, from a bitstream, information about a maximum size of a coding unit, information about a maximum depth indicating a total number of possible times a maximum coding unit is split, and split information indicating whether a coding unit of a current depth is split into coding units of a lower depth; determining a plurality of maximum coding units by dividing a picture using the information about a maximum size of the coding unit; determining, based on the split information, coding units of a hierarchical structure comprising coding units which are not split any more among coding units split from each maximum coding unit among the plurality of maximum coding units; and decoding the coding units of the hierarchical structure in the each maximum coding unit, wherein: the each maximum coding unit is hierarchically split into coding units of depths including at least one of a current depth and a lower depth according to the split information, a minimum coding unit among the coding units is determined by splitting the each maximum coding unit by the maximum depth, and when the a size of the coding unit (900, 930, 960) of the current depth is greater than a size of the minimum coding unit, the split information is obtained for the coding unit of the current depth from the bitstream, when the split information indicates a split for the coding unit of the current depth, the coding unit of a current depth is split into coding units of the lower depth by dividing a height and width of the coding unit of a current depth by two, and when the split information indicates a non-split for the coding unit of the current depth, a plurality of prediction units are determined in the coding unit of the current depth and inter prediction is performed on the plurality of prediction units, a transformation unit is determined from the coding unit of the current depth and inverse transformation is performed on the transformation unit.