A video encoding apparatus includes: a predictor to generate a predicted block of a current block corresponding to a predicted motion vector and a differential motion vector; and an entrophy encoder to encode an index for use in identifying the predicted motion vector of the current block and the differential motion vector in a bitstream, where the predicted motion vector of the current block corresponds to a motion vector identified by the index in an inter prediction mode, and where the index corresponds to at least one of representative blocks determined using neighboring blocks of the current block, in consideration of priorities of block positions.