An apparatus for decoding a video, the apparatus comprising: an extractor configured to extract, from a received bitstream, information about a maximum size of a coding unit, and split information indicating whether a coding unit of a current depth is split into coding units of a lower depth; and a decoder configured to determine a plurality of maximum coding units by dividing a picture using the information about a maximum size of the coding unit, determine, 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 decode the coding units of the hierarchical structure in the each maximum coding unit, wherein the decoder is configured to hierarchically split the each maximum coding unit into coding units of depths including at least one of a current depth and a lower depth according to the split information, when the split information indicates a split for the coding unit of the current depth, the decoder is configured to split the coding unit of a current depth into coding units of the lower depth by dividing a height and width of the coding unit of a current depth by two, characterized that: when the split information indicates a non-split for the coding unit of the current depth, the decoder is configured to determine a plurality of prediction units in the coding unit of the current depth, perform inter prediction on the plurality of prediction units, determine one or more transformation units in the coding unit of the current depth and perform inverse transformation on the transformation units. an extractor configured to extract, from a received bitstream, information about a maximum size of a coding unit, and split information indicating whether a coding unit of a current depth is split into coding units of a lower depth; and a decoder configured to determine a plurality of maximum coding units by dividing a picture using the information about a maximum size of the coding unit, determine, 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 decode the coding units of the hierarchical structure in the each maximum coding unit, wherein the decoder is configured to hierarchically split the each maximum coding unit into coding units of depths including at least one of a current depth and a lower depth according to the split information, when the split information indicates a split for the coding unit of the current depth, the decoder is configured to split the coding unit of a current depth into coding units of the lower depth by dividing a height and width of the coding unit of a current depth by two, characterized that: when the split information indicates a non-split for the coding unit of the current depth, the decoder is configured to determine a plurality of prediction units in the coding unit of the current depth, perform inter prediction on the plurality of prediction units, determine one or more transformation units in the coding unit of the current depth and perform inverse transformation on the transformation units. when the split information indicates a non-split for the coding unit of the current depth, the decoder is configured to determine a plurality of prediction units in the coding unit of the current depth, perform inter prediction on the plurality of prediction units, determine one or more transformation units in the coding unit of the current depth and perform inverse transformation on the transformation units.