PURPOSE: To provide a retro-focus type scanning objective lens in which aberration is corrected over a wide scanning range.

CONSTITUTION: The scanning objective lens consists of a first lens group G1 having negative refracting power and a second lens group G2 having positive refracting power force. The G1 is formed out of concave meniscus lenses L1, L2, and the G2 is formed out of a composed lens consisting of a convex meniscus lens L3, a concave meniscus lens L4 and a convex lens L5, and a composed lens consisting of a convex lens L6, a concave meniscus lens L7, and a convex meniscus lens L8. When the focus distances of the G1 and G2 are F1, F2, the refraction index of L1, L2 is N1, the refraction index of L3 and L8 is N2p, the refraction index of L4, L7 is N2cn, and the refraction index of L5, L6 is N2cp, expressions of N1>1.6, N2P>1,6, N2cn-N2cp>0.2, 2<F1<10, and 2<F2/ F1<6 are satisfied.