An electrical device includes a thermistor and at least two electrodes electrically connected to the thermistor and to which a source of electrical power is applied to cause current to flow through the thermistor. The thermistor may be a composite and includes a polymer material; and a plurality of conductive carbon nanotubes distributed in the polymer material. The electrical device employed with the thermistor performs not only PTC property, but also NTC property. Moreover, the method for fabricating the electrical device is also simple and easy to carry out because of the simple process.