Provided are methods and apparatuses for encoding and decoding a motion vector. The method of encoding a motion vector includes: selecting a mode from among a first mode in which information indicating a motion vector predictor of at least one motion vector predictor is encoded and a second mode in which information indicating generation of a motion vector predictor based on pixels included in a previously encoded area adjacent to a current block is encoded; determining a motion vector predictor of the current block according to the selected mode and encoding information about the motion vector predictor of the current block; and encoding a difference vector between a motion vector of the current block and the motion vector predictor of the current block.