PURPOSE: To eliminate a material loss at the time of manufacturing a mandrel, to eliminate the need of a process for disassembling the mandrel and to easily feed a heat resisting thread, to improve stability of a shape, to have a three- dimensional follow-up property, and to enhance productivity by large holding force.

CONSTITUTION: A mandrel 4 is formed by cutting a first notch 3b and a second notch 3d on a continuous belt-like steel plate 3 so as to be arrayed alternately in the long size direction, expanding and forming it to an expand metal shape in which diamond arch shaped being long in the width direction are continued in the long size direction and rolling it to a plane. Subsequently, this garnish is formed by feeding at least two pieces of heat resisting threads or wires 2 so as to be separated by necessary dimensions on both sides from the center line in the width direction on one side, garnishing them, and molding them in a main body web 1.