PURPOSE: To adjust an eccentric aberration and to improve optical characteristics by arranging negative lens which have large refracting power in front of and behind a diaphragm, and fixing eccentrically at least one of plural positions lenses provided on the image side of said lenses.

CONSTITUTION: The two negative lenses G4 and G5 are arranged across the diaphragm so that their concave surfaces face the stop side, and ≥1 lenses are provided in front of and behind the lenses G4 and G5. The concave surfaces set across the stop S are large in refracting power, so the eccentric aberration is generated over the entire image plane if there is an eccentricity error in the assembly. For the purpose, at least one of lenses elements in a position lens group G8 arranged on the image side of the lens G5 is made eccentric by being slanted to the optical axis or moved in parallel. Consequently, the eccentricity aberration resulting from manufacture and assembly is adjusted to obtain a lens group with variable optical characteristics which maintains high optical performance.