DC CIRCUIT BREAKER

Provided is a DC circuit breaker capable of interrupting a failure current in both directions which flows in a DC transmission line when a failure occurs in the DC transmission line. The DC circuit breaker includes: a first mechanical switch connected to a first DC transmission line at a first side thereof, and connected to a first conductive connecting member at a second side thereof; a second mechanical switch connected to the first conductive connecting member at a first side thereof, and connected to a second DC transmission line at a second side thereof; a first diode connected to the first mechanical switch in parallel; a second diode serially connected to the first diode through the second conductive connecting member, and connected to the second mechanical switch 120 in parallel; and a semiconductor switching circuit switching a flow of a failure current when a failure occurs.