A motion vector detection method includes extracting a first block from the m-th picture, extracting second blocks having a large correlation with respect to the first block from a (m+n)-th picture ((m+n)>m-th), detecting first motion vectors between the first and second blocks, extracting a third block located in spatially the same position as that of the first block from a (m+i)-th picture ((m+n)>(m+i)>m-th), computing second motion vectors of (n−1)/n times the first motion vectors, extracting a fourth block corresponding to a movement position of the third block from the (m+n)-th picture according to the second motion vector, and selecting an optimum motion vector maximizing a correlation between the third and fourth blocks from the first motion vectors.