Voltage variable resistors comprising a sintered wafer consisting essentially of zinc oxide (ZnO), 0.05 to 8.0 mole percent of bismuth oxide (Bi2O3) and 0.05 to 10.0 mole percent of at least one member selected from the group consisting of niobium oxide (Nb2O5), zirconium oxide (ZrO2), vanadium oxide (V2O5) and tungusten oxide (WO3) and two electrodes applied to opposite surfaces of said sintered wafer, at least one of said two electrodes being a silver paint electrode.