A moving-vector detecting device and a moving-vector detecting method are provided to reduce an arithmetic operation quantity for the detection of moving-vectors and prevent an image from deteriorating. A moving-vector detecting device (1) comprises a first moving-vector extracting circuit (142) for extracting reducing number of first vectors from a plurality of the first vectors detected by a first vector detecting circuit (141), and a selecting circuit (143) for selecting either the plurality of the first moving-vectors or the extracted first moving-vectors.