Glass-ceramics includes Li2O, Al2O3 and SiO2, have an average crystal grain diameter of a predominant crystal phase of 90 nm or below and have crystal grain diameter distribution of 20 nm or below. The glass-ceramics can be manufactured by heat treating glass comprising Li2O, Al2O3 and SiO2 under a temperature within a range from 650° C. to 750° C. and then further heat treating the glass under a temperature within a range from 700° C. to 800° C. for 100-200 hours.