A smart earth leakage circuit breaker is installed on a distribution line through which an electric current flows. The breaker measures, by means of a CT, a leakage current flowing through the distribution line, and if the measured current exceeds a preset rated sensitivity current, cuts off electricity by means of trip operation. The smart earth leakage circuit breaker further comprises: a measurement unit tracking and measuring, based on measurement information of the CT, a value of the leakage current exceeding an alarm current value; the MPU setting conditionality and the alarm current value less than the rated sensitivity current and when the conditionality is satisfied based on information measured by the measurement unit, issuing a warning by means of an alarm unit; and the alarm unit operated and controlled by the MPU and warning of an abnormal symptom of the distribution line.