Optical glass, precision press-molding preform and optical element

A process for producing an optical element, which comprises machining a glass shaped material formed of an optical glass that is a fluorine-containing glass that exhibits a transmittance except for reflection loss at a sample surface, measured in a sample 10 mm thick having two flat surfaces parallel with each other at a wavelength of 400 nm to 2,000 nm, of 80% or more, and has a refractive index nd(1), wherein the absolute value of nd(2)−nd(1) is 0.00300 or less, said refractive index nd(2) being a refractive index of the fluorine-containing glass after the fluorine-containing glass is re-melted in a nitrogen atmosphere at 900° C. for 1 hour, cooled to its glass transition temperature and then cooled to 25° C. at a temperature decrease rate of 30° C./hour.