Zirconia sol and method for manufacturing same

A zirconia sol,

• wherein the zirconia sol has a transmittance of 45% or more at a wavelength of 400 nm, has a transmittance of 75% or more at a wavelength of 550 nm, and contains zirconia particles in an amount of 20 wt % or more;
• and
• wherein the zirconia sol contains an alkali metal oxide (M2O, M indicates an alkali metal) with respect to zirconia in an M2O/ZrO2 mole ratio of 0.02×10−2 or more and 0.4×10−2 or less.