PURPOSE: To provide high optical performance and also to lessen the decrease of a zoom ratio in the case of focusing to an object in a short distance by performing focusing in a state where a lens group including a front lens group is moved in a different ratio in accordance with a zooming position on an optical axis.

CONSTITUTION: This device is provided with plural lens groups including a variable power lens group L2 moved on the optical axis in order to perform variable power, and a correcting lens group L3 correcting image surface fluctuation accompanying the variable power; and the focusing is performed by moving at least two lens groups including the front lens group L1 among the plural lens groups in the different ratio in accordance with the zooming position on the optical axis. Since the magnification of the front lens group L1 is always fixed irrespective of the zooming position, the zoom ratio is prevented from being decreased in the zoom lens performing front lens focusing. The front lens group L1 largely affects aberration fluctuation on a telephotographic side, and the front lens group L1 is used as the focusing lens group, so that the aberration caused by the focusing lens group other than the front lens group L1 can be reduced.