An optical system includes a negative lens satisfying the following conditional expressions: 30≤νd≤40, 1.225≤[nd−(14.387/νd)]≤1.276, and 0.4300≤[θgF−(2.9795/νd)]≤0.5010, where νd is an Abbe number of the negative lens, θgF is a partial dispersion ratio of the negative lens at a g-line and an F-line, and nd is a refractive index of the negative lens at a d-line.