Disposed herein is an abnormal current detection circuit for circuit breaker, comprising a full-wave amplifier 202, a positive wave-period comparator 203 for comparing a positive wave-period amplification voltage signal with a positive wave-period reference voltage signal to output a pulse signal, a negative wave-period comparator 204 for comparing a negative wave-period amplification voltage signal with a negative wave-period reference voltage signal to output a pulse signal, a combining circuit 206 for combining pulse signals outputted from the positive wave-period comparator and the negative wave-period comparator to output a full-wave combining signal, a reference voltage generator 209 for generating a reference voltage signal, and a comparative driving circuit section 208 for comparing the combining signal with the reference voltage signal to output a signal for controlling a circuit breaker to be driven to a circuit breaking position when the combining signal is greater or equal to the reference voltage
