PURPOSE: To reduce the deterioration in picture quality such as the enlargement and the doubling. etc., of a horizontal line due to an interpolation display with relatively small-scaled circuit constitution by interpolating a video signal at least by one horizontal scanning at every prescribed number of horizontal scanning the display of the video signal.

CONSTITUTION: If an interpolation display part is assumed to be the eighth line L8 in a liquid crystal pannel 1, and the video signal by one horizontal scanning displayed on the seventh line L7 and the ninth line L9 of front and rear of the L8 are defined the seventh and the eighth video signals of one field, first of all, the seventh video signal is divided into four sections, and is thinned in a comb-shape in section, and the eighth line L8 is interpolation-displayed at intervals by the remaining signals. Then, the next eighth video signal is divided into four sections also, and the signal in the section not corresponding to thinned section of the former video signal is thinned in a comb-shape in section, and a part jumped by the former signal of the eighth line L8 is interpolation-displayed by the remaining section signals. In such a manner, when the number of sections of the video signal by one horizontal scanning are increased, the horizontal line is looked on the horizontal line as the luminance of 1/2 as the whole, and the fact that the horizontal line is enlarged due to the interpolation display is reduced.