A thermistor includes a first electrically conductive member, a second electrically conductive member and a polymer material layer laminated therebetween. The polymer material layer exhibits positive temperature coefficient (PTC) behavior, and includes at least one crystalline polymer and at least one electrically conductive filler distributed in the crystalline polymer. The conductive filler has a resistivity less than 500 μΩ-cm and includes 72-96% by weight of the polymer material layer. The thermistor has a device effective area, and the value of the hold current at 60° C. divided by the device effective area is around 0.16-0.8 A/mm2. The ratio of the hold current of the thermistor at 60° C. to the hold current at 25° C. of the thermistor is 40-95%.