To obtain a compact and high zoom ratio zoom lens system which exhibits excellent performance in the total focal length range using a lens construction having only a small number of lenses by reducing a total lens length and a front lens effective diameter on the long focal length end.

The high variable power zoom lens system is constructed of a positive first lens group, a negative second lens group, a positive third lens group and a negative fourth lens group starting from the object side in this order and satisfies the following inequalities: (1) 0.2<LD23W/fW<0.70, (2) 0.02<ΔD23/fW<0.2, (3) 11<|fT/f2|<14 (f2<0) and (4) 12<fT/f3<15, wherein LD23W is the distance from an object side surface of the second lens group to the image side surface of the third lens group on the short focal length end, ΔD23 is the difference between the distance from the second lens group to the third lens group at the short focal length end and that at the long focal length end, fi is the focal length of the i-th lens group (i = 2, 3), fW is the focal length of the total system at the short focal length end and fT is the focal length of the total system at the long focal length end.