Method and apparatus for predictive encoding/decoding of motion vector

A video decoding apparatus for predicting a current block to be decoded, the apparatus comprising:

• a bitstream decoder configured to extract an index for use in identifying a predicted motion vector of the current block and a differential motion vector from a bitstream;
• and
• a predictor configured to generate a predicted block of the current block based on the predicted motion vector and the extracted differential motion vector,
• wherein the predicted motion vector of the current block is determined to be a motion vector identified by the extracted index in a motion estimation mode of an inter prediction mode, and
• wherein the extracted index corresponds to one or more representative blocks determined using neighboring blocks of the current block, in consideration of priorities of block positions,
• wherein the one or more representative blocks are determined in considering of a difference between a first picture order count (POC) corresponding to a first reference picture of a neighboring block and a second picture order count (POC) corresponding to a second reference picture of the current block when a first inter prediction direction corresponding to the neighboring block and a second inter prediction direction corresponding to the current block are identical.