A Bismuth glass composition including 0.5 to 14 wt % of SiO.sub.2, 3 to 15 wt % of B.sub.2O.sub.3, 4 to 22 wt % of ZnO, 55 to 90 wt % of Bi.sub.2O.sub.3 and 4 wt % or less of Al.sub.2O.sub.3, and further including 5 wt % or less of an oxide of Group A, 12 wt % or less of an oxide of Group B and 0.1 to 10 wt % of an oxide of Group C, wherein the oxide of Group A is at least one selected from the group consisting of Li.sub.2O, Na.sub.2O and K.sub.2O, the oxide of Group B is at least one selected from the group consisting of MgO, CaO, SrO and BaO, and the oxide of Group C is at least one selected from the group consisting of Sc.sub.2O.sub.3, Y.sub.2O.sub.3, La.sub.2O.sub.3, CeO.sub.2, Pr.sub.2O.sub.3, Nd.sub.2O.sub.3, Sm.sub.2O.sub.3, Eu.sub.2O.sub.3, Gd.sub.2O.sub.3, Tb.sub.2O.sub.3, Dy.sub.2O.sub.3, Ho.sub.2O.sub.3, Er.sub.2O.sub.3, Tm.sub.2O.sub.3, Yb.sub.2O.sub.3 and Lu.sub.2O.sub.3.