Disclosed is a zoom lens herein. The zoom lens has a first group G1 having a negative focal length, a second group G2 having a positive focal length and a third group G3 having a positive focal length in turn from an object side, and has an opening iris S for moving integrally with the second group G2 on the object side of the second group G2, wherein in variation of magnification from a short focus end to a long focus end, the second group G2 moves monotonously from image side to object side and the first group G1 moves to correct the variation in position of image surface accompanying the variation of magnification. The second group G2 consists of four elements of a positive lens L4, a negative lens L5, a positive lens L6 and a positive lens L7 in turn from the object side.