Gas circuit breaker

To provide a gas circuit breaker having a space-saving and highly reliable double motion mechanism with high design freedom. In a double motion mechanism of the gas circuit breaker, a driven side movable pin is communicated with a lever driven side hole cut in the opposite side with respect to a rotation axis of a lever. A round hole through which a driving side movable pin is inserted and an elongate hole through which the driven side movable pin is inserted are cut in the outside of the lever. A position retaining member to suppress rotation of the driving side movable pin about two axes vertical to a pin axis is provided. The driving side movable pin is moved in respective grooved cams with an operation of the driving side rod, to rotate the lever, drive the driven side connecting rod in an opposite direction to the driving side connecting rod, and drive the driven side arcing contact in an opposite direction to the driving side arcing contact.