An electromagnet mechanism is coaxially disposed with a vacuum interrupter that is disposed in a circuit breaker, and has a movable core and a fixed core facing each other and an electromagnetic coil that makes the movable core and the fixed core separate or come into contact in response to electromagnetic force. A driving rod which is movably disposed in the axial direction of the electromagnet mechanism is coupled to the movable core, and in which one side is coupled to the circuit breaker and the other side passes through an opening side end plate of the electromagnet mechanism to be extended outward from the opening side end plate of the electromagnet mechanism. An indication unit is disposed on the opening side end plate of the electromagnet mechanism, and indicates a state of the circuit breaker in conjunction with the movement of the driving rod.