To provide a tripolar or bipolar circuit breaker which can provide desired tripolar and bipolar switches by mounting a core selectively in a common molding die and which can contribute to a reduction in manufacturing cost by using either of the switches as needed.

Each of tripolar and bipolar switches, 15, 16, respectively, has an opening 30 on each side of an insulating material 29 in the center of which a working part 28 for connection to a tripping mechanism is formed, with a movable arm inserted into the opening 30. The tripolar switch 15 has in its center a center opening 31 into which the movable arm is inserted and a recess 32 formed at the edge of the center opening 31 to enable the movable contact of the movable arm to pass through the opening, and also has an imitating part 33 of approximately the same shape as the working part 28, between the opening 30 on one side and the center opening 31. The bipolar switch 16 has a recess 32 at the edge of the opening 30 on one side, that enables the movable contact to pass through the opening, and has an imitating part 33 at its end.