More accurate frame-rate conversion is carried out in a simpler circuit configuration. Search areas SA+1 and SA−1 in each of which the pixel facing the interpolation position P0 of a pixel in an interpolation frame is taken as a central pixel are set in the current frame and immediately previous frame of an image signal, a set of pixels point-symmetrical to the interpolation position P0 in each of the search areas SA+1 and SA−1 are defined as pixel pairs, and differential luminance values between the individual pixels in the pixel pairs are calculated for each pixel pair. Of all these pixel pairs, only that having the minimum absolute differential value is selected as interpolation pixel pair, an interpolation frame is generated from the current frame and the immediately previous frame on the basis of the interpolation pixel vector of that interpolation pixel pair.