Realized is a shape of a grooved cam that maximizes break performance by appropriately setting an electrode operation with a minimum weight increase. A gas circuit breaker includes a drive side electrode (2) and a driven side electrode (4) which are disposed to face each other in a sealed tank (100), the drive side electrode has a drive side main electrode and a drive side arcing electrode, the driven side electrode has a driven side main electrode (3) and a driven side arcing electrode (5), the drive side arcing electrode is connected to an operating device (1), and the driven side arcing electrode is connected to a double motion mechanism portion (10), in which the double motion mechanism portion includes a drive side connection rod (11) that receives a driving force from the drive sideelectrode, a driven side connection rod (13) that is connected to the driven side arcing electrode, a lever (12) that is bent to the operating device side around a rotation axis by causing the drivenside connection rod to operate in an opposite direction with respect to an operation of the drive side connection rod, and a guide (14) that defines operations of the drive side connection rod and thedriven side connection rod.