A circuit breaker that utilizes pressurized gas produced by the generation of arcs and that is compact and has a high cut-off performance. The circuit breaker comprises a stator (33) having a fixed contact (34), a turnable movable element (31) having at one end a movable contact (32) connectible to and disconnectible from the fixed contact (34) and at the other end a center of rotation (31a), a case (3) surrounding the stator (33) and movable element (31) and defining a pressure accumulation space on one side of the arc generating position whereby the gas pressurized by the arcs produced between the fixed contact (34) and the movable contact (32) upon current cut-off is temporarily retained on one side of the arc generating position, and an exhaust port (39) formed on the other side of the arc generating position in the case (3) such that the pressurized gas retained in the pressure accumulation space upon current cut-off is exhausted through between the fixed contact (34) and the movable contact (32).
