To provide an inexpensive compact zoom lens which secures a zoom ratio of about three times.

When zooming is performed from a wide angle end to a telephoto end, a first negative lens group I temporarily is moved to the image surface side and then is moved to the object side, and a second positive lens group II is moved to the object side integrally with an aperture stop SD , and a third positive lens group III is moved to the image surface side. Each of the first to third lens groups includes at least one plastic lens, and the first to third lens groups are formed so as to satisfy conditional expressions 0.9≤|fG1|/fG2≤1.5 and 1.0≤|1/fP1+1/fP2+1/fP3|×fw≤3.0 wherein; fG1 and fG2 are focal lengths of the first lens group and the second lens group respectively; fw is a focal length of the lens system at the wide angle end; and fP1, fP2, and fP3 are focal lengths of plastic lenses included in the first lens group, the second lens group, and the third lens group respectively. Thus the inexpensive zoom lens having a zoom ratio of about three times is obtained.