A pattern matching section compares reference taps supplied by one area extracting section with a reference tap component of a training pair pre-stored in a training-pair storing section, selects a training pair including a reference tap component having highest similarity to the reference taps, and supplies the selected training pair to a normal-equation generating section. Training pairs stored in the training-pair storing section include a SD signal and HD signal. A prediction-coefficient determining section obtains prediction coefficients by solving normal equations generated by the normal-equation generating section. A prediction calculating section produces a HD signal by applying the prediction coefficients to prediction taps extracted by another area extracting section.