The present invention relates to a method and apparatus for encoding/decoding image using a motion vector.According to one embodiment of the present invention, an image-decoding method is provided. The image-decoding method comprises the following steps: clipping a motion vector of a reference picture with a predetermined dynamic range so as to generate a clipped motion vector; storing the clipped motion vector in a buffer; deriving a motion vector of a block to be decoded using the motion vector stored in the buffer; and performing inter-prediction decoding using the motion vector of the block to be decoded. According to the present invention, the size of a memory space required to store a motion vector may be reduced.