An optical system includes an optical element. When the optical element is disposed on a magnification side with respect to an intersection point between an optical axis and a chief paraxial ray, the optical element is a positive lens. When the optical element is disposed on a reduction side with respect to the intersection point, the optical element is a negative lens. The optical element satisfies all of the following conditional expressions: 30≤νd≤40 1.225≤[nd−(14.387/νd)]≤1.276 0.4300≤[θgF−(2.9795/νd)]≤0.5010 where νd is Abbe number of the optical element, θgF is a partial dispersion ratio of the optical element for g-line and F-line, and nd is a refractive index of the optical element for d-line.