PURPOSE: To provide an automatic twisting tester which enables an accurate and efficient testing to be realized by performing a twisting test of a cable of a lightning arrestor for power distribution automatically.

CONSTITUTION: A guide 21 is installed in an insulator holder 4 for lightning arrestor matching an arrestor 1 for power distribution. A rod 5 and rod guide 19 are arranged slidable in the insulator holder 4 for the arrestor and a spring 14 is provided to energize the rod 5 to the side of a bolt 6. A tubular part is formed at a closed part of the insulator holder 4 for the arrestor and connected to a rotating shaft of a moor 15 through a gear 11 and a gear 10. The rod 5 is connected to a sequencer 25 through a connection cord 7c. A hole 2a is formed in a weight 2 to let a cable 3 pass therethrough while being provided with a clamp 24 for fixing the cable and a connection cord 7a is connected for the connection of the cable. The weight 2 is connected to the sequencer 25 through an electrode plate, an electrode 27, a frame and an AC/DC power source 26.