A gas circuit breaker includes movable and fixed electrode parts arranged to face each other in an engaging/separating manner in a container filled with an insulating gas, an operating mechanism attached to a partition of the container and configured to output an operating force to the movable electrode part, an operating rod attached to the movable electrode part, a first link rotatably attached to the operating rod, a lever rotatably attached to the first link, a support bearing fixed to the partition of the container via an insulating spacer, a second link rotatably attached to the lever and also rotatably attached to the support bearing, a seal bearing connected through the partition of the container, a seal rod rotatably attached to the center of the lever and slidably supported to the seal bearing, and a third link rotatably attached to the seal rod and also attached to the operating mechanism.