To prevent damage of a case, and also reduce the cross directional dimension by arranging each circuit breaker part, in which the electromagnetic force by the current flowing in both contacts develops the electromagnetic repulsion for resisting the spring pressure, in parallel with three phases, and arranging the circuit breaker part of an intermediate layer while being displaced in a direction for reducing the electromagnetic force of the circuit-breaker part of other phases.

Each movable contact 501 provided under each movable contact carrier 500R, 500S, 500T of three-phase of the RST phase structure pushes each fixed contact 401 of each fixed contact carrier 400R, 400S, 400T. A circuit breaker part, in which the electromagnetic force by the current flowing in both the contacts 501, 401 develops the electromagnetic repulsion force for resisting the spring pressure, is arranged in parallel with the three-phase of the RST phase structure with an equal space. A circuit breaker part of the S phase as an intermediate phase is arranged while being displaced to a position for forming a triangle, and a handle for switching the movable contact is provided over the movable contact carrier 500S. With this structure, cross directional dimension can be reduced.