To provide a system which does not change an angle of view at mode switching even in an easy case where a single focus lens is used, in an image pickup device which has two or more types of different modes in an area read out of an image pickup element.

From a circuit which produces a pulse which drives an image pickup element, different areas read out of an image pickup element in each mode are detected, and an electronic zoom magnification is computed from the change amount of the areas between the modes, and a video signal is multiplied by an electronic zoom at this magnification, so that the change of an angle of view at switching can be eliminated.