PURPOSE: To smoothly drive a photographing lens to a focusing point without unstable actions such as hunting, etc., by detecting the accurate position of the focusing point even in case of driving the photographing lens during the charge accumulating time of an image sensor.

CONSTITUTION: When the photographing lens 13 moves while accumulating the charges of the charge accumulation type image sensor 15, the moving position of the photographing lens 12 and what is called defocusing in the position are continuously detected. A functional information generating means 21 generates the functional information between defocusing and the movement quantity of the photographing lens 12 and a recording means reads and stores the functional information of the functional information generating means 21 at both points of the charge accumulating start point and completion point of the charge accumulation type image sensor 15. And the moving direction and movement quantity of the photographing lens to the focusing position are computed from the functional information at both points and the position of the photographing lens 12 at present. Thus, the photographing lens can be surely located in the focusing point.