The tape is free from any slack and separation even when it is applied and bonded to a metal joint portion while being bent. The tape, made of an unvulcanized material containing an unvulcanized rubber-base material, a vulcanization accelerator, an anti-oxidizing agent, a pigment and a bulk filler, is formed into an elongated shape having an upper and a lower surface and a predetermined thickness measured in a direction perpendicular to the lower surface or flat bottom surface 1. The upper surface forms a circularly-curved surface 2 in cross section. Since the tape is in an unvulcanized state, it is capable of being free bent when applied to the metal joint portion. After application of the tape to the metal joint portion, a paint is applied to the tape, which is followed by a heating process in which the tape is heated, and, therefore vulcanized.