The present disclosure relates to a detecting circuit for a circuit breaker, comprises: a detection sensor configured to output a detection signal by detecting a voltage or a current on an alternating current electric power circuit; a low pass filter configured to output a signal from the detection sensor after removing a high frequency component from the signal; an offset remover configured to output a signal from the low pass filter after removing a direct current offset from the signal; an amplifier configured to amplify a signal from the offset remover, and to output the signal; and a comparator configured to output a breaking control signal such that the circuit breaker operates to a circuit breaking position, if the detection signal input to the amplifier is equal to or larger than a reference voltage.