To make the length of back focus long and to restrain aberration with good balance while attaining a wider viewing angle and high resolution by constituting a wide-angle lens of three lens groups being negative, positive and positive and making it satisfy specified conditional expressions.

The 1st lens group L1, the 2nd lens group L2 and the 3rd lens groups L3 to L6 are arrayed in order from an object side. Then, they satisfy a conditional expression I: 0.8<Bf/f<1.1, a conditional expression II: 1.1<f1-2G/f<1.5, a conditional expression III: 1.4<f3G/f<2.1, a conditional expression IV: 3.0<f6/f<4.5, a conditional expression V: 1.72<N2, a conditional expression VI: 1.77<N3 and a conditional expression VII: νd3<30. Provided that Bf is the back focus of a lens entire system when an object distance is infinite, (f) is the focal distance of the lens entire system, f1-2G is the synthetic focal distance of the 1st and the 2nd lens groups, f3G and f6 are the fcal distances of the 3rd and the 6th lens groups, N2 and N3 are the refractive indexes of the 2nd and the 3rd lens groups to a d-line, and νd3 is the Abbe number of the 3rd lens group to the d-line.