The current limiting circuit breaker comprises a circuit breaker (1A) and at least one current limiting unit (1B); the circuit breaker (1A) has load side terminals (12) and power-source-side or connection terminals (2a), and the current limiting unit (1B) is unitized to be simply connected to the circuit breaker (1A) or to another current limiting unit (1B) at their power source side terminals; the current limiting unit (1B) has current limiting connection terminals (25a) which ride on the circuit breaker connection terminals (2a) or power-source-side terminals (20a) of another current limiting unit (1B) for connection, to the circuit breaker (1A) or another current limiting unit (1B).