On condition that a first lens group adopts at least one plastic lens; a second lens group adopts at least any two adjacent plastic lenses; the first lens group monotonously moves from an object side to an image plane side in a zooming; the second lens group monotonously moves from the image plane side to the object side; wherein fw/fpi represents a ratio of refractive power of the entire system achieved at a wide angle end to refractive power of the respective lenses; P1 represents a total of fw/fpi of the plastic lenses of the first lens group; and P2 represents a total of fw/fpi of the plastic lenses of the second lens group, the following conditional expressions −0.22