A glass sheet includes, as represented by mole percentage based on oxides, from 55.5 to 80% of SiO2, from 12 to 20% of Al2O3, from 8 to 25% of Na2O, 2.5% or more of P2O5, and 1% or more of an alkaline earth metal RO (RO is MgO+CaO+SrO+BaO).