PURPOSE: To provide the subject caulking device which can caulk with an improved coupling strength and in an improved appearance, by method wherein a thin sheet- form heater is positioned at an end surface of a support bar, having a cooling unit, through the medium of a heat-resistant electric insulation sheet, and both ends of heater are connected to a sequence control power source.

CONSTITUTION: A cooling section 2, in which a great many fins are formed radially, is mounted monolithically at a surrounding of a columnar support rod 1 made of a metal having an improved heat-conductivity, and a heat-resistant insulation sheet 3, such as polyamid resin sheets, glass woven fabrics, is applied to one end of the support rod 1, emerging from the cooling section 2, so that the end surface and an outer circumference of the end portion are covered with said resin. A thin sheet- form heater 4, in which a nichrome ribbon is press-molded, is covered thereon, and both ends are connected to a sequence control power source. Accordingly, a processing temperature can be produced by just electrifying the heater 4 momentarily and can fall rapidly by turning off the electricity thereby, permitting a reliable and good- finishing molding by caulking.