PURPOSE: To perform the switching of a circuit breaker momentarily, and judge the condition of the circuit breaker, which is under one of the ON, OFF and trip condition.

CONSTITUTION: When a reversible motor 34 is rotated normally or reversely, a converting mechanism 37 converts this rotation to the movement of a movable body 36 in the arrow E direction and the arrow F direction. With the movement of the movable body 36, an ON operating body 46 and an OFF operating body 47 push and contract compression springs 52, 53 to move them to original positions P1, P2. When the lock of the OFF operating body 47 locked with the terminal position P2 is cancelled, the OFF operating body 47 is moved at a high speed in the arrow E direction by the stored energizing elastic force of the compression spring 53 to move a handle 5 at a high speed to the OFF position. When the lock of the ON operating body 46 is cancelled, the ON operating body 46 is moved at a high speed in the arrow F direction by the stored energizing elastic force of the compression coil 52 to move the handle 5 at a high speed to the ON position. Condition of the circuit breaker is judged on the basis of the switching of the handle 5 between an ON position side switch 62 and an OFF position side switch 63.