PURPOSE: To facilitate manufacturing and downsize an outward form by reducing the number of insulated shafts.

CONSTITUTION: A linear guide 8 is provided on the inner side of one side of an outer frame 1, and an insulated frame 3 is fixed to the moving side 8b of the linear guide 8. A vacuum bulb 2 and a moving contact 7, connected to the fixed side of the vacuum bulb 2, are contained inside the insulated frame 3. A guide plate 9 is fixed to the inside of the other side of the outer frame 1 via an insulator 16, and an approximately arrowhead-shaped groove 9a is formed in the guide plate 9. A pin 11 is fixed to the tip of the moving shaft 13 of the vacuum bulb 2, and the pin 1 is fitted to the groove 9a with play. An operating shaft 5 is provided passing through the outer frame 1 in a perpendicular direction to the axis of the vacuum bulb 2, and the tip of the lever 15 of the operating shaft 5 is connected to the insulated frame 3 via a pin 14.