To improve current-limiting breaking performance of a circuit breaker by changing the current path, which runs through a stationary and movable contactor, to a loop-shape so that all currents flowing in the stationary and a movable contactor at the time of short-circuit breaking can be effectively utilized for fast movable contactor opening and extended arc drive.

A circuit breaker having a current cutoff part, a make-and-break mechanism part and an overcurrent drawing part mounted inside a main body case comprises: a pair of stationary contactors 7, 8 whose current cutoff parts respectively extend to a power supply side terminal and a load side terminal; a bridge type movable contactor 9; a direct-acting contactor holder having the movable contactor 9 mounted therein and communicates with the make-and-break mechanism part; and a pair of arc-extinguishing chambers 12 disposed along a contact parting path of the movable contactor on both sides thereof. In the circuit breaker, the power supply side and load side stationary contactors 7, 8 are constructed in such a way that their contactor conductors are extended from one end of the movable contactor 9 to the other end on the opposite side, and extended parts 7b, 8b thereof are provided with stationary contacts 7a, 8a disposed at both ends of the movable contactor 9 and opposed to a movable contact 9a.