Video decoding method and computer readable redording meduim using motion vector

The present invention relates to a video encoding / decoding method and apparatus of using a motion vector. The image decoding method according to an embodiment of the present invention includes the steps of generating a motion vector cut by cutting a motion vector of a plane of reference pictures in a predetermined range, the method comprising: deriving a motion vector of the current block using the motion vector , and it may include the step of performing the inter-prediction decoded using the motion vector of the current block. According to the invention it is possible to reduce the amount of memory space required to store a motion vector.