At least one exemplary embodiment is directed to a zoom lens which includes, in order from an object side to an image side, a first lens unit with a negative refractive power, a second lens unit with a positive refractive power, and a third lens unit with a negative refractive power. The second and third lens units move during zooming. The first lens unit includes a negative biconcave lens element. The zoom lens satisfies the following conditions: -1.4<.phi.1/.phi.w<-1.0 0.9<.phi.2/.phi.w<1.4 -1.3<.phi.3/.phi.w<-0.9 where .phi.1 is a refractive power of the first lens unit, .phi.2 is a refractive power of the second lens unit, .phi.3 is a refractive power of the third lens unit, and .phi.w is a refractive power of the entire system at a wide-angle end.