Optical glass, preform and optical element

The invention provides optical glass, a preform and an optical element. Provided is an optical glass which has a refractive index and an Abbe number within a desired range and is suitable for an optical element that contributes to light weight and stability of an optical device. The optical glass contains, in mass%, 15.0 to 35.0% of a B2O3 component, 20.0 to 41.58% of a La2O3 component, 3.0% or less of an Nb2O5 component, 3.0% or less of a WO3 component, 0.1% or less of a Ta2O5 component, and 6.00% or less of a ZrO2 component, has a refractive index of 1.80 or more, an Abbe number of 35 to 40, and a specific gravity of 4.80 or less, the mass sum of an Ln2O3 component is 20.0 to 41.58%, Ln is one or more selected from La, Gd, Y, and Yb, and (Nb2O5 + WO3)/(La2O3 + Gd2O3 + Ta2O5) is 0.05 or less. 光学玻璃、预成型体及光学元件。更廉价地提供光学玻璃，折射率及阿贝数在期望的范围内，适合于有助于光学设备的轻质化稳定的光学元件。光学玻璃按质量％计含有15.0～35.0％的B2O3成分、20.0％～41.58％的La2O3成分，Nb2O5成分的含量为3.0％以下，WO3成分为3.0％以下，Ta2O5成分为0.1％以下，ZrO2成分为6.00％以下，光学玻璃具有1.80以上的折射率、35～40的阿贝数和4.80以下的比重，Ln2O3成分的