The present invention provides a thermal caulking device which can quickly heat and cool an object to be caulked with low electrical power. Provided is a thermal caulking device which caulks a portion of a plastic part 7 as an object to be caulked, the thermal caulking device including: a metal tip 3 having a pressing part 3a which presses the object to be caulked and a heating rod 3c which is provided upright at a center part of the pressing part 3a; heating means 10c for heating the heating rod 3c; a cooling pipe 9 which cools the heating rod 3c; cooling fluid supply means 4 for supplying a cooling fluid to the cooling pipe 9; a holder 1 which holds the metal tip 3 and the cooling pipe 9 so that the cooling pipe 9 delivers the cooling fluid toward the heating rod 3c; and control means 6 for controlling the heating means 10c and the cooling fluid supply means 4, wherein the control means 6 heats the pressing part 3a from the heating rod 3c by the heating means 10c, and after the object to be caulked is thermally caulked by the pressing part 3a, supplies the cooling fluid from the cooling fluid supply means 4 to the cooling pipe 9 to cool the pressing part 3a from the heating rod 3c.