Provided are a motion vector predicting method and an apparatus for encoding and decoding a video. The motion vector prediction method includes: determining, from neighboring blocks of the current block, a plurality of candidate blocks that are referred to so as to predict a motion vector of a current block; determining a candidate motion vector of a first candidate block among the determined plurality of candidate blocks, based on whether a reference image of the first candidate block and a reference image of the current block are long-term reference images; and determining the motion vector of the current block by using a candidate motion vector list including the determined candidate motion vector of the first candidate block and candidate motion vectors from remaining candidate blocks among the determined plurality of candidate blocks.