A circuit breaker comprising a controller and an isolation mechanism of the controller, characterized in that the isolation mechanism comprising: a first connector that has a plurality of output terminals electrically connected to the controller and a plurality of input terminals detached from the output terminals for connecting an input electric power source; and a second connector, characterized in that the second connector has a first connection position connected to the first connector and a second connection position rotated at 180° from the first connection position and connected to the first connector, and has a conductor wiring portion electrically connecting the output terminals with the input terminals at the first connection position and electrically disconnecting the output terminals from the input terminals at the second connection position, wherein the first connector comprises a plurality of first invalid conductor wiring portions (MP2, MP3, MP5, MP8) that are formed to be detached from the output terminals and the input terminals, having no electric connection with the output terminals and the input terminals, and wherein the conductor wiring portion of the second connector comprises a plurality of connection wiring portions (CP1, CP2) that connect the output terminals with the input terminals at the first connection position and connect the plurality of first invalid conductor wiring portions (MP2, MP3, MP5, MP8) at the second connection position; and wherein the second connector comprises a plurality of second invalid conductor wiring portions (SP1, SP2, SP3, SP4) that are connected to the first invalid conductor wiring portions (MP2, MP3, MP5, MP8) at the first connection position and connected to the output terminals and the input terminals at the second connection position, and formed to be detached from one another. a first connector that has a plurality of output terminals electrically connected to the controller and a plurality of input terminals detached from the output terminals for connecting an input electric power source; and a second connector, characterized in that the second connector has a first connection position connected to the first connector and a second connection position rotated at 180° from the first connection position and connected to the first connector, and has a conductor wiring portion electrically connecting the output terminals with the input terminals at the first connection position and electrically disconnecting the output terminals from the input terminals at the second connection position, wherein the first connector comprises a plurality of first invalid conductor wiring portions (MP2, MP3, MP5, MP8) that are formed to be detached from the output terminals and the input terminals, having no electric connection with the output terminals and the input terminals, and wherein the conductor wiring portion of the second connector comprises a plurality of connection wiring portions (CP1, CP2) that connect the output terminals with the input terminals at the first connection position and connect the plurality of first invalid conductor wiring portions (MP2, MP3, MP5, MP8) at the second connection position; and wherein the second connector comprises a plurality of second invalid conductor wiring portions (SP1, SP2, SP3, SP4) that are connected to the first invalid conductor wiring portions (MP2, MP3, MP5, MP8) at the first connection position and connected to the output terminals and the input terminals at the second connection position, and formed to be detached from one another.