An object is to provide a glass for chemical toughening treatment satisfying low brittleness, low melt viscosity and high chemical toughening characteristics, and a chemically toughened glass using the same. Provided is a glass for chemical toughening treatment containing, in mass % in terms of oxides, SiO2 63 to 76, B2O3 0 to 2, Al2O3 2 to 10, MgO 2 to 12, CaO 0.1 to 8, Na2O 14.5 to 19, K2O 0 to 3, and Fe2O3 0 to 0.5, satisfying a total content of alkali earth metal oxides (RO) being from 5 to 15, satisfying 15×MgO/RO−RO≥3, and having a temperature T2 at which a glass viscosity reaches 102 dPa·s being 1,600° C. or lower.