A DC circuit breaker of the type using a blown arc-extinguishing gas is disclosed which allows for reliable fast interruption of DC currents through the provision of arc extension current paths. The extension current paths are relatively long and are bent after the incidence of the arc-extinguishing gas on the arc. The arc is formed to extend for a long distance in a loop configuration. An auxiliary electrode short-circuits the extended arc with one auxiliary electrode being provided for each extension current path.