To protect a metal pipe from dielectric breakdown arising from potential rise due to induced lightning and prevent damage to the metal pipe.

An insulating tape 2 is applied to the surface of the metal pipe 1, and a metal shielding layer 3 is formed thereon and is grounded. Thus, if the potential of a steel skeleton portion 4 rises, damage to the metal pipe 1 due to dielectric breakdown can be prevented by causing dielectric breakdown in the steel skeleton portion 4 and the metal shielding layer 3. Further, damage to the metal pipe 1 can be prevented against higher lightning impulse voltages by forming the metal shielding layer 3 in an area equivalent to 70% or less of the protected area protected by the insulating tape 2 in terms of the length from the center of the protected area.