PURPOSE: To save labor, and concurrently enhance working efficiency by automatically connecting insulators to each other and driving a cutter pin of the insulator.

CONSTITUTION: An insulator 1 which has a cutter pin 8 inserted in the pin insertion hole of a cap fitting 3 in advance, is carried in to a connecting position P1 by a connecting mechanism 15, and the insulator 1 is connected to an insulator which has been previously carried into the connecting position P1, in a state that its axial line is bent. The cap fitting 3 to the lately carried insulator 1 is then connected to the pin fitting 5 of the previously carried insulator 1. Under this condition, the cutter pin 8 of the lately carried insulator is driven therein by a pin driving mechanism 24. The previously carried insulator 1 is held by a holding and moving mechanism 27, and concurrently the whole set of insulators is moved intermittently by a specified pitch.