To provide a tripping circuit capable of preventing a wrong tripping of a breaker inadvertently when a voltage of an inner power source changes.

A trip coil 15 of a breaker 12, a first relay contact 19 of b-contact, and a second contact 20 of a-contact are connected in series between a 24V power source line of an inner power source and a GND power source line. An operation switch 16 and a first relay coil 21 are connected in series between the 24V power source line and the GND power source line. A second relay coil 22 is connected between the 24V power source line and the GND power source line. Wrong working prevention circuits (24, 25) carry out a status change of a first relay RL1 at an inner power source voltage lower than that carrying out a status change of a second relay RL2.