A glass, which is a glass for a magnetic recording medium substrate or for a glass spacer for a magnetic recording and reproducing apparatus, is an amorphous oxide glass. An SiO2 content ranges from 56 mol % to 80 mol %, an Li2O content ranges from 1 mol % to 10 mol %, a B2O3 content ranges from 0 mol % to 4 mol %, a Na2O content is 0 mol %, a total content of MgO and CaO (MgO+CaO) ranges from 9 mol % to 40 mol %, and the oxide glass has a specific gravity of 2.75 g/cm3 or less, a glass transition temperature of 650° C. or higher, and a Young's modulus of 90 GPa or more.