A ZnO varistor powder can be obtained with high operating voltage and excellent current-voltage nonlinear resistance characteristics. In the ZnO varistor powder, the main ingredient is zinc oxide (ZnO); and at least bismuth (Bi), cobalt (Co), manganese (Mn), antimony (Sb), nickel (Ni), and aluminum (Al), calculated as Bi2O3, CO2O3, MnO, Sb2O3, NiO, and Al3+, are contained as accessory ingredients in amounts of 0.3 to 1.5 mol % Bi2O3, 0.3 to 2.0 mol % Co2O3, 0.3 to 3 mol % MnO, 0.5 to 4 mol % Sb2O3, 0.5 to 4 mol % NiO, and 0.0005 to 0.02 mol % Al3+. ZnO content is greater than or equal to 90 mol %; the bulk density is greater than or equal to 2.5 g/cc; the powder is a spherical powder in which the 50% particle diameter in the particle size distribution is 20 μm to 120 μm.