A zoom lens device has a zoom lens system having a plurality of lens units; and an image sensor converting an optical image formed by the zoom lens system, into electric image data. The zoom lens system has, from the object side, a first lens unit disposed on the most object side and consisting of one negative lens element; and a second lens unit being overall positive power and including a positive lens element and a negative lens element independent of each other. Lens surfaces constituting the zoom lens system are all refracting surfaces. Zooming is performed by varying the distances between the lens units. The predetermined conditions are satisfied by the zoom lens system.