PURPOSE: To provide a gas disconnecting switch of high reliability capable of reducing a voltage level of disconnector surge, generated at reignition time, by carrying a current by a resistance contact and a fixed side contact part through a resistor with a reignition arc surely leading to the resistance contact from a movable contactor, by reducing probability where the reignition arc generated from the movable contactor is flash-shorted to the fixed side contact part.

CONSTITUTION: Here are assumed D1 for diameter of an opening part 20 of a resistance contact 19, L for interpole length which is the dimension of length between poles (between movable side contact part 2 and resistance contact 19) of a gas disconnecting switch and 1 for thickness of the opening part 20 in the axial direction of a movable contactor 11 in the opening part 20 of the resistance contact 19. Here is formed the constitution so as to obtain 67% ratio D1/L of the opening part diameter D1 to the interpole length L and 40% ratio l/D1 of the opening part thickness l to the opening part diameter D1.