A glass composition of the present invention relates to a multicomponent oxide glass composition manufactured by melting glass raw materials, which contains: 10 ppm or more of at least one type of a polyvalent element; minimum valence cations of the polyvalent element in a ratio of the minimum valence cation content to the total polyvalent element content of 5 to 98% in mass ratio; and 0.01 to 2 .mu.l/g (0.degree. C., 1 atm) of helium.