PURPOSE: To provide a device of which thermal efficiency is high, electric power consumption is small, size is small, and reliability and durability are excellent, concerning a heating device to prevent icing of the throttle body of the carburetor or the electronic fuel injection device of an internal combustion engine using gasoline or the like.

CONSTITUTION: In this heating device, the heating element 10 is formed into a plate, a positive characteristic thermister is used as a heating member, and the current characteristic and temperature characteristic suitable for preventing icing are provided. Supporting members 11, 12 electically conductive and having excellent thermal conductivity are arranged between the heating element and a heat sink 16 having electric conductive property and formed so as to closely contact one-side faces with the inner face of the heat sink. Further, an electrode member 15 having spring property is arranged between the two heating elements so as to fix the heating elements and press them against the supporting members, and hence favorable electric conductivity and thermal conductivity are realized. In a heating system, the heating device is controlled by a PTC timer using a positive characteristic thermistor.