Provided is an optical glass having a small Abbe number (nud), a small partial dispersion ratio (thetag, F), heightened transparency with respect to visible light, and a refractive index (nd) within a desired range. Also provided is a preform and an optical element in which the optical glass is used. The optical glass contains, in terms of mass, 5.0 to 40.0% of an B2O3 component, 15.0 to 60.0% as a sum of the mass of an Ln2O3 component (where Ln is one or more elements selected from the group consisting of La, Gd, Y, and Yb), and 0 to 50.0% of an Nb2O5 component. With respect to the Abbe number (nud), the partial dispersion ratio (thetag, F) satisfies the relationship (-0.00162 × nud + 0.63822) <= (thetag, F) <= (-0.00275 × nud + 0.68125) in the range where nud <= 31, and satisfies the relationship (-0.00162 × nud + 0.63822) <= (thetag, F) <= (-0.00162 × nud + 0.64622) in the range where nud > 31.