The present disclosure relates to a semiconductor circuit breaker and, more specifically, to a semiconductor circuit breaker in which a protection circuit is modularized and thus maintenance and repair can be easily done. A semiconductor circuit breaker according to an embodiment of the present disclosure comprises: a main circuit unit connected between a power source and a load and having a semiconductor switch; an outer box equipped with the main circuit unit and having a module accommodation unit outside thereof; and a protection module detachably accommodated in the module accommodation unit.