Provided is a method that generates a prediction block of a current prediction unit, and generates a residual block of the current prediction unit. To generate the prediction block, a reference picture index and motion vector difference of the current prediction unit are obtained from a received bit stream, spatial and temporal motion vector candidates are derived to construct a motion vector candidate list. A motion vector predictor is selected and a motion vector of the current prediction unit is restored to generate the prediction block. Therefore, the motion vector encoded effectively using spatial and temporal candidates is correctly recovered and the complexity of a decoder is reduced.