Method for etching alkali-free glass substrate and display device

Disclosed is a method for etching the surface of an alkali-free glass substrate which contains one or more metals selected from the group consisting of Ca, Sr, Ba and Mg. In this etching method, the surface of the alkali-free glass substrate is etched by using an etchant containing no NH4F, wherein HF and HCl satisfy (A) HF is not less than 5% by mass but less than 20% by mass and HCl is not less than 9% by mass, (B) HF is not less than 20% by mass but less than 30% by mass and HCl is not less than 5% by mass, or (C) HF is not less than 30% by mass and HCl is not less than 2% by mass.