An optical system includes a negative front group having a component of first and second lenses cemented together, an aperture stop, and a positive rear group. The component has: a first face, on the front-direction-object side of the first lens, having a first transmitting surface and an annularly-formed first reflecting surface facing the image side a second face, at the cemented surface, having a second transmitting surface and an annularly-formed second reflecting surface facing the front-direction-object side a third face as a transmitting surface on the image side of the second lens and a fourth face as a transmitting circumferential face of the first lens. The component satisfies the conditions: nd&mdashRL1&minusnd&mdashRL2<0.3 vd&mdashRL1&minusvd&mdashRL2<40 where nd&mdashRL1 and nd&mdashRL2 are refractive indices for d line, of the first and second lenses, respectively, and vd&mdashRL1 and vd&mdashRL2 are Abbes numbers for d line, of the first and second lenses, respectively.
