PURPOSE: To obtain the heat-sensitive element with improved impedance characteristics with respect to temperature, which comprises a copolymerized polyamide, primarily composed of an undecanoamide unit and/or a dodecanoamide unit, and a specified condensed amino unit.

CONSTITUTION: 95W60wt% of an undecanoamide unit (e.g., 11-aminoundecanoic acid) and/or a dodecanoamide unit (e.g., 12-aminododecanoic acid), are mixed with 5W40wt% of a condensed amide unit obtained by the reaction of trimethylhexamethylenediamine and a dicarboxylic acid of the formula (wherein n is 4W10) (e.g., adipic acid or sebacic acid), and the resulting mixture is subjected to polycondensation by being heated to 200W300°C together with a suitable amount of water, to obtain a copolymerized polyamide. The purposed heat-sensitive element is obtained by extruding the polyamide into the form of an electrical heating wire, a sheet form, etc., by means of an extruder, etc.