PURPOSE: To provide the voltage-withstanding insulating tube, of a lightning- resistant horn, in which an electrode metal fitting can be fixed easily to an end part and which can be worked at low costs and to provide the bonding structure and the bonding method of the metal fitting to the voltage-withstanding insulating tube.

CONSTITUTION: A plurality of through holes 1a are made in the insulating tube. A grounding-side electrode metal fitting 3 and a power-supply-side electrode metal fitting 4 are fitted to both end parts of the insulating tube 1. Caulking parts 3a, 4a which correspond to the through holes 1a in both metal fittings 3, 4 are pressed by pressure molds whose shape corresponds to the through holes 1a, and they are deformed so as to be caulked. When the caulking parts 3a, 4a are caulked by the pressure molds, the caulking parts for the electrode metal fittings 3, 4 are sunk into the through holes 1a by a desired amount, and both electrode metal fittings 3, 4 are bonded to the insulating tube 1.