A direct-current circuit breaker includes a circuit breaker unit and a circuit unit that generates an oscillating current. The circuit unit includes a capacitor and a reactor, a high-speed closer, and a lightning arrester. The circuit breaker unit and the high-speed closer are aligned in a first direction with a distance therebetween that is equal to or longer than a certain spatial distance. The capacitor and the lightning arrester are aligned in a second direction intersecting the first direction with a distance therebetween that is equal to or longer than the spatial distance. A combination of the circuit breaker unit with the high-speed closer and a combination of the capacitor with the lightning arrester are aligned in a third direction intersecting the first direction and the second direction with a distance therebetween that is equal to or longer than the spatial distance.