The earth leakage circuit breaker of the present disclosure includes a leakage current detection unit outputting a leakage current detection signal; a conversion unit outputting the leakage current magnitude of a fundamental wave component, a ratio of a third harmonic component, and a ratio of a positive pole peak current value to a negative pole peak current value; and a control unit comparing the leakage current magnitude of a fundamental wave component, the ratio of a third harmonic component, and the ratio of a positive pole peak current value to a negative pole peak current value with predetermined reference values to determine whether a leakage current of the alternating current component is generated or a leakage current of the direct current component is generated and to thereby output a trip control signal when it is determined that the leakage current of the direct current or alternating current component is generated.