Abstract: A highly reliable gas circuit breaker capable of improving the braking performance and the insulating performance and a gas circuit breaker capable of allowing a stress acting on the supporting member of the electrode are provided. The gas circuit breaker comprising a grounded tank filled with an insulation medium; a movable electrode arranged inside the grounded tank; a fixed electrode which is supported through an insulator supporting member inside the grounded tank and disposed detachably from and oppositely to the movable electrode; and electric conductive parts individually provided in the movable electrode and the fixed electrode, wherein the insulator supporting member is a solid cone and supports the fixed electrode in an upper side of a central axis of the grounded tank.