A method for generating a prediction block in Advanced Motion Vector Prediction (AMVP) mode to reconstruct a prediction-coded video signal using a motion vector approximate to original motion information. An AMVP candidate list is generated using effective spatial and temporal AMVP candidates for a current Prediction Unit (PU). If the number of the effective AMVP candidates is smaller than a predetermined value, a motion vector having a predetermined value as a candidate to the AMVP candidate list. Then a motion vector corresponding to an AMVP index of the current PU from among motion vectors included in the AMVP candidate list is determined to be a motion vector predictor of the current PU.