A double rate processing part generates, at a double rate, a non-interlaced image signal every frame to twice generate a double-rate non-interlaced signal which has identical information duplicately. An interlace part, after a predetermined process is carried out on the double-rate non-interlaced signal twice generated by the double rate processing part, extracts an odd scan lines from one of the twice generated double-rate non-interlaced signal to generate an odd scan line image signal, extracts an even scan lines from the other of the twice generated double-rate non-interlaced signal to generate an even scan line image signal, so as to obtain an interlaced image signal for one frame.