A varistor comprises an element body, two external electrodes, and a metal conductor. The element body includes a portion having first and second faces opposing each other. Two external electrodes are arranged on the first face of the element body. The metal conductor is arranged on the second face of the element body. The metal conductor has a thermal conductivity higher than that of the element body. At least a region between the two external electrodes and metal conductor in the element body exhibits a nonlinear current-voltage characteristic. The heat transmitted to the varistor is efficiently diffused from the metal conductor in the varistor.