PURPOSE: To prevent a direct lightning strike on a lightning arrester and to keep the performance of the lightning arrester sound by providing a direct lightning strike preventing horn which is connected electrically to a pylon and surrounds three-dimensionally the outside circumference of the lightning arrester in respect to the pylon, with a prescribed insulation distance held therefrom.

CONSTITUTION: A direct lightning strike preventing horn 10 comprises three arm parts 10a, 10b and 10c the upper ends of which are fixed to a support member 6 and lower parts of which extend in three directions except the pylon 1 side around a lightning arrester 7, and a horizontal part 10d which is connected to the lower ends of these arm parts 10a, 10b and 10c in common and surrounds the lower part of the lightning arrester 7 within a horizontal plane except the pylon 1 side. According to this constitution, the outside circumference of the lightning arrester 7 is surrounded three-dimensionally by the direct lightning strike preventing horn comprising the arm parts 10a, 10b and 10c and the horizontal part 10d. An overvoltage relating to an insulator string 3 is suppressed by a gap (g) between horn electrodes 8 and 9.