A varistor includes a varistor element, a first layer which is porous on the varistor element, and a second layer on th first coating. The thickness t (mm) of the second layer is not smaller than 1.3/V. where V(ml/g) is the volume of pores of the first layer exposed to an outside of the first layer. This varistor includes the outer layers protected from being broken even when a non-ohmic interface in a voltage non-linear resistor is broken down with a voltage exceeding a rated level.
