A circuit breaker comprising a vacuum valve; an electromagnet including a first coil for driving an operating shaft of the vacuum valve toward an opening direction by electromagnetic repulsion, a movable core and a permanent magnet; and an operating mechanism which excites the first coil to close the vacuum valve, holds the vacuum valve closed by an attractive force of the permanent magnet and excites the first coil in a direction reverse to an excitation direction in closing operation to open the vacuum valve. In the circuit breaker, together with the first coil, a second coil which is excited simultaneously with an electromagnetic repulsion coil for electromagnetic repulsion in quick opening operation by electromagnetic repulsion is provided in the electromagnet.