A tempered glass substrate has a compression stress layer on a surface thereof, and has a glass composition comprising, in terms of mass %, 40 to 70% of SiO2, 12 to 21% of Al2O3, 0 to 3.5% of Li2O, 10 to 20% of Na2O, 0 to 15% of K2O, and 0 to 4.5% of TiO2, wherein the tempered glass substrate has a plate thickness of 1.5 mm or less, and an internal tensile stress in the tempered glass substrate is 15 to 150 MPa.