The invention provides a circuit breaker. The circuit breaker comprises a housing, a contact system, a transmission system, a release system, a driving motor and an operation handle. The transmission system comprises a driving member, a transmission member, a first transmission member and a second transmission member, wherein a second elastic member is arranged between the second transmission member and the housing, a first elastic member is arranged between the first transmission member and the housing. The release system comprises a release shaft, and the first transmission member is provided with a trigger portion abutting against the release shaft; when a user is in default, the driving motor drives the first transmission member to press against the release shaft, and the contact system is open; and when the user pays a fee, the driving motor continues to rotate, the release shaft is no longer pressed, the first transmission member turns around under the elastic force effect of the first elastic member, and the contact system is driven to be closed through the second transmission member. Therefore, before the user pays an electricity bill, even if an operation handle is manually turned to be closed, since the release system is at a trigger state, the operation handle is automatically reset to an opening position, and the user cannot draw power by himself.