Wide-angle lens

A wide-angle lens is provided, which comprises a first lens, a second lens, a third lens, a fourth lens and a fifth lens sequentially arranged from an object side to an image side, wherein the refractive indexes of the first, second, third and fourth lenses are negative, positive, positive and negative, respectively. The wide-angle lens satisfies the following conditions: -0.05 < ((1/f1)+(1/f2)+(1/f3)+(1/f4)+(1/f5)) < 0.14 and 1.01 < (((N3-1)/(1/f3))*((1/R6)-(1/R7))) < 1.2, wherein f1, f2, f3, f4 and f5 respectively represent the focal lengths of the first, second, third, fourth and fifth lenses, N3 is the refractive index of the third lens, and R6 and R7 respectively represent curvature radiuses of an object side and an image side of the third lens. The wide-angle lens of the present invention provides a better optical quality.