Dielectric relaxation was observed in a porous glass (Corning 7930), and its characteristics were the same as those of oxide glass. When pores of the porous glass were removed by heat treatment at 1200°C, the dielectric relaxation disappeared. The porous glass was reduced to powder and a solid sample was made by heating the powder at 1400°C. Characteristics of the dielectric relaxation of the sample were different from those of oxide glass. These results suggest that the dielectric relaxation of oxide glass is ascribable to microscopic conducting path structure of the interconnected structure type.