PURPOSE: To provide the titled thin lightweight glass contg. SiO2, B2O3, Na2O, K2O, Li2O, TiO2, etc. in a specified weight ratio, having a high refractive index and low specific gravity, and covering a low diopter region having a great demand.

CONSTITUTION: Starting materials such as silica powder, aluminum hydroxide, titanium oxide, borax, potassium carbonate and magnesium carbonate are blended so as to prepare a composition consisting of, by weight 56W67% SiO2, 0W7% B2O3, 0W5% AlO3, 0W11% Na2O, 0W10% K2O, 0W7% Li2O (11W18% Na2O+K2O+ Li2O), 13W19% TiO2, 0W4% MgO+CaO+SrO+ZnO and 0W2% La2O3+ZrO2+ Nb2O3, and the blend is heated to a high temp. to obtain the titled glass. This glass has ≥1.59 refractive index, ≥36 Abbe's number and ≤2.6 specific gravity.