DIRECT CURRENT CIRCUIT BREAKER

A direct current circuit breaker includes a first breaking unit and a second breaking unit. The first breaking unit includes: a first circuit breaker inserted in a direct current line; and a resonance circuit unit that generates a resonance current. The first breaking unit forms a current zero point by superimposing the resonance current on a direct current flowing through the direct current line, and breaks the direct current by opening the first circuit breaker. The second breaking unit includes a semiconductor element, allows the direct current to flow when energization of the semiconductor element is ON, and breaks the direct current by switching energization of the semiconductor element from ON to OFF.