A method of encoding a video, which performs deblocking filtering based on coding units. The method includes determining a filtering boundary on which deblocking filtering is to be performed based on at least one data unit from among coding units that are hierarchically configured according to depths indicating a number of times at least one maximum coding unit is spatially spilt, and prediction units and transformation units respectively for prediction and transformation of the coding units, determining filtering strength at the filtering boundary based on a prediction mode of a coding unit to which adjacent pixels belong based on the filtering boundary, and transformation coefficient values of pixels adjacent to the filtering boundary, and performing deblocking filtering based on the determined filtering strength.