A rear focus type zoom lens for an image capturing element, comprising, in the order from the object side: a first lens group having a positive refracting power; a second lens group having a negative refracting power and movable for variable magnification; a third lens group having a positive refracting power; and a fourth lens group having a positive refracting power and movable for correcting positional change of an image plane in variable magnification. When .nu.1 represents Abbe's number of at least one piece of positive lenses of the first lens group, .nu.31 represents Abbe's number of a single lens, fi represents a focal length of an i.sup.th lens group and f4- represents a focal length of the negative lens in the fourth lens group, the following conditional expressions are satisfied: 75.0<.nu.1, 40.0>.nu.31, 0.8