A zoom lens is disclosed to comprise sequentially from an object side, a first lens group having an negative refracting power, and being movable back and forth along with an optical axis when a zooming rate is changed, a second lens group having a positive refracting power, and being movable to the object side along with the optical axis when the zooming rate is changed from a wide-end to a tele-end; and a third lens group movable back and forth along with the optical axis, and having a positive refracting power. In such zoom lens, the second lens group includes sequentially from the object side, an iris, one piece of convergent lens where at least a surface facing to the object side is an aspherical surface and an adhered three pieces of lenses.