To detect a leak position quickly and easily as a position in one of branch circuits divided by branch breakers, and remove that position so as to make the other normal branch circuits operate normally.

After the power distribution line of a power user enters a main breaker 1 and a leakage current detector 2, the distribution line is divided into a plurality of branch circuits 41-48 by a plurality of branch breakers 31-38. If leak is detected by the leakage current detector 2 while a power is supplied through the power distribution line the main breaker 1 is opened in accordance with the command of a breaker control circuit 5 and then the branch breakers 31-38 are opened. After all the branch breakers 31-38 are opened, the main breaker 1 is closed. After that, the branch breakers 31-38 are closed one by one. If the leak is detected by the leakage current detector 2 when one branch breaker is closed, the branch breaker of that branch circuit is opened and kept in the open state to remove the leaking circuit.