A bismuth-based glass composition includes as a glass composition, in terms of mass %, 55% to 80% of Bi2O3, 15% to 35% of SiO2, 0% to less than 3% of ZrO2, 0% to 5% of B2O3, and 0% to less than 8% of ZnO, and has a mass ratio SiO2/ZrO2 of more than 6.7.