ZOOM LENS SYSTEM

PROBLEM TO BE SOLVED: To provide a zoom lens system having a high zoom ratio such as ten or more in spite of having a simple constitution. SOLUTION: This lens system is constituted of a 1st lens group Gr1 having positive power, a 2nd lens group Gr2 having negative power, a 3rd lens group Gr3 having positive power and a 4th lens group Gr4 having positive power in order from the object side. In the case of performing zooming from the wide angle end to telephoto end, at least the 1st, the 3rd and the 4th lens groups Gr1, Gr3 and Gr4 are moved to the object side and the 2nd, the 3rd and the 4th lens groups Gr2, Gr3 and Gr4 have at least one aspherical surface, respectively.