The electric conductivity of a densified Na2O.3SiO2 glass with a density of 2.539 g/cm3 was measured at temperatures from 90 to 160-degrees-C after the heat treatments at various temperatures up to the glass transition temperature. The structural relaxation started at about 200-degrees-C, and correspondingly the isotherm conductivity (120-degrees-C) increased towards that of undensified glass. But, there was little change in the activation energy. The obtained results are attributed to a change in the pathways for the migration of sodium ions.