An average luminance calculation section 7 calculating an average luminance of video data to output an average luminance level, latches 8 to 10 delaying said average luminance levels by one-frame portion respectively to output them, a LUT 2 outputting a pre-set maximum correction factor e when the video data is input, correction factor calculation sections 3 to 6, adders 11 and 12, and a multiplier 12 are provided, each of the correction factor calculation sections compares the corresponding average luminance level out of the average luminance levels, which were output, with a plurality of correction thresholds respectively to carry out weighting of the maximum correction factor e responding to the comparison result and to output it as each correction factor, and simultaneously the adders 11 and 11, and the multiplier 12 correct the luminance level of the video data based on the average value of these correction factors.