To provide an earth leakage breaker involving no risk that the arc gas causes inter-electrode shortcircuiting of a copper bar on the power supply side and that eventual leakage damages a leak sensing circuit.

An opening/closing part 8 is provided on the load side inside a case 1 divided vertically, while the leakage sensing circuit 22 is installed on the power supply side. An arc gas exhaust hole 12 generated in the opening/ closing part 8 may be formed on the load side of the case 1, and the copper bar on the power supply side due to arc gas can be prevented from causing inter-electrode shortcircuiting. Power leads 14 of the leakage sensing circuit 22 are led through a groove 15 provided at the bottom of the case 1 in consolidation and connected with an electric path part on the side nearer the load than the opening/closing part 8, which will eliminate the risk of damaging a tripping coil 23 of the leakage sensing circuit 22 in the event of current leakage.