PURPOSE: To improve magnification chromatic aberration while keeping compact property and to obtain excellent workability by dividing a converging lens group arranged immediately after a diaphragm into two groups and setting up the Abbe numbers of respective groups to different values.

CONSTITUTION: A lens arranged immediately before the diaphragm consists of a divergent lens having a concave face on its image side, the convergent lens group Gp arranged immediately after the diaphragm is constituted of the 1st optical element consisting of a parallel plane glass and the 2nd optical element consisting of a plane convex lens turning its convex face to the image side and respective Abbe numbers ν2, ν3 are set up to the relation of ν2<ν3. The magnification chromatic aberration is effectively corrected by the 1st element and the refractive index of the 2nd element is set up to ≥1.7 so that the chromatic aberration is not increased while keeping the thickness of an edge. Thereby, the magnification chromatic aberration can be sufficiently corrected by dividing the convergent lens group and the compact property and workability of the lens can be improved.