The invention provides a zoom lens, wherein the zoom lens realizes miniaturization of diameter of a front lens and shortens total length of the lens system in light axis direction apart from maintaining high optical performance. The zoom lens comprises four lens assemblies from a first lens assembly (G1) to a forth lens assembly (G4). The first lens assembly (G1) and the third lens assembly (G3) are fixed, and the second lens assembly (G2) is moved when zooms in or out, and the forth lens assembly (G4) is moved to correct image plane position of the zoom and focus. The first lens assembly (G1) comprises a negative lens and two positive lens. The second lens assembly (G2) comprises four lens with one negative lens having a aspheric surface. The following conditional expression (1), (2) aresatisfied: 6.0