A method of predicting a motion vector for a current block in a current picture includes obtaining, by the moving picture decoding device, at least three motion vectors for at least three blocks other than the current block based on a direction of a reference picture, wherein the direction of the reference picture is based on a display order of the reference picture and a display order of the current picture, the at least three motion vectors correspond to the at least three other blocks, respectively, and the at least three blocks are not in an intra mode, predicting, by the moving picture decoding device, the motion vector for the current block by using a median operation of the at least three motion vectors and decoding the current block in the current picture using the predicted motion vector for the current block.