PURPOSE: To reduce unnecessary movement of a focusing lens and to shorten the time up to focusing, and to prevent malfunction by moving at least two lens groups Z among plural lens groups of a zoom lens for zooming so that an image plane position is held constant to a close-distance body.

CONSTITUTION: The movement area of a lens group F is specified by points P, P', Q, and Q' and when the lens group F is on a line PP', a close-distance body is in focus. At this time, the line PP' is parallel to a line VV' which is a movement trace formed by the zooming of a lens group V1 in front of the lens group F. When the close-distance body is put in focus where the base of the lens group V1 and that of the lens group F about to each other, the lens group F never moves closer to the body than the line PP'. Therefore, zooming from a zoom position Z1, i.e. point A to a wide angle side is performed to move the lens group F in contact with the line PP', and focusing moves from a wide-angle side point A' to a point A" by an automatic focusing function.