To provide an earth leakage breaker capable of improving workability of a conductor to a zero-phase-sequence current transformer and surely insulating the conductor of respective electrodes from each other.

Respective conductor plates 221 to 223 penetrating through a zero-phase-sequence current transformer 35 are insulated from each other by an inter-electrode insulation barrier 42, by arranging the inter-electrode insulation barrier 42 to the inside of the zero-phase-sequence current transformer 35. By the above, it becomes unnecessary to cover respective conductor plates 221 to 223 one by one, the conductor plates are prevented from becoming thick and easily penetrated through the zero-phase-sequence current transformer 35, and the size of the conductor plates 221 to 223 can be reduced as a whole by appropriately bending them. By the above, the conductor plates can be easily fitted into the earth leakage breaker.