LIGHTNING ARRESTER

PROBLEM TO BE SOLVED: To provide a lightning arrester which requires no preparation of a different metal mold each time the size of a zinc oxide element block such as the height and the magnitude in a diameter direction changes, and therefore has no need to fabricate various tightening members. SOLUTION: A tightening member 15 is made of one piece of insulation string having a first expanded locking section 15a and a second expanded locking section 15b on both end parts. At both end parts of the tightening member 15, the first locking section 15a and the second locking section 15b are locked in a locking section 12b, with a middle part being locked continuously in a fourth locking groove 22c, a second locking groove 13a, a first locking groove 12a, a third locking groove 13b, and again the fourth locking groove 22c.