An optical glass with constant refractory index and Abbe's number is provided to inhibit generation of milk-whitening and devitrifaction inside the glass during press molding or reheating process by comprising Bi2O3 or a combination of Bi2O3 and alkali metal or alkali-earth metal oxide. The optical glass has refractory index of [nd] of more than 1.75 and Abbe's number of [vd] of more than 10. The optical glass contains 10 to 90wt.% of Bi2O3 and represents substantially no milk-whitening and/or devitrifaction inside the glass in a reheating test(a) comprising the steps of: reheating a specimen with size of 15mm x 15mm x 30mm; raising temperature by 80deg.C higher than transition temperature(Tg) of the specimen; keeping the temperature for 30 minutes; naturally cooling the specimen to ordinary temperature; then visibly observing both faces of the specimen after polishing the faces to thickness of 10mm.