An optical glass that contains Si, Al, Mg, and O is provided. The optical glass contains Si in an amount of 40% or more and 60% or less, in cation percent, Al in an amount of 10% or more and 35% or less, in cation percent, and Mg in an amount of 20% or more and 35% or less, in cation percent. In the optical glass, the total amount of Si, Al, and Mg is 99.5% or more, in cation percent. Furthermore, the optical glass contains Fe and Na each in an amount of 0.01 wtppm or less and has a transmittance to a light having a wavelength of 248 nm of 40% or more at a thickness of 5 mm.