PURPOSE: To allow easy control of trip time without altering the material of thermister element itself and dimensions thereof by thermally coupling a material, having thermal conductivity different from that of a thermister board constituting a PTC thermister element, with the PTC thermister element.

CONSTITUTION: Ohmic Ag and Ag paste are printed and fired on the opposite side faces of a PTC thermister substrate 12 thus forming opposing electrodes 13, 14. Phosphor bronze plates(having different thermal conductivity) 16 are secured through a conductive adhesive 15 to the outer side faces of the electrodes 13, 14. The temperature-sensitive element comprises the substrate 12, the electrodes 13, 14, the adhesive 15, and the phosphor bronze plates 16. When a material having desired thermal conductivity is coupled while selecting dimensions thereof, trip time can be determined easily depending on the application without altering the material of PTC thermister element itself and dimensions thereof.