1. An apparatus for encoding a current motion vector of a current block in a current frame into a bitstream by determining a predicted motion vector corresponding to the current motion vector of the current block, the apparatus comprising: a prediction candidate selector configured to select one or more motion vector prediction candidates from among motion vectors of blocks in the current frame and motion vectors of blocks in a reference frame to determine the predicted motion vector corresponding to the current motion vector; a predicted motion vector determiner configured to determine the predicted motion vector among the one or more motion vector prediction candidates; and a differential motion vector encoder configured to calculate a differential motion vector by subtracting the predicted motion vector from the current motion vector, and encode the differential motion vector, wherein the prediction candidate selector comprises: means for selecting one or more first motion vector prediction candidates from one or more blocks adjacent to the current block in the current frame, and means for selecting a second motion vector prediction candidate from a block located in the reference frame other than the current frame, wherein the block, from which the second motion vector prediction candidate is selected, in the reference frame is derived based on a position of the current block in the current frame.