A DC current breaking device provided in a DC power transmission circuit in which at least a first DC power transmission line and a second DC power transmission line are electrically connected to each other at a first connection point (j), the DC current breaking device comprising: a first mechanical switch provided in the first DC power transmission line; a second mechanical switch provided in the second DC power transmission line; a first auxiliary line electrically connected to a first position (j3-1) located on the side opposite to the first connection point (j) with respect to the first mechanical switch in the first DC power transmission line; a second auxiliary line electrically connected to a second position (j3-2) located on the side opposite to the first connection point (j) with respect to the second mechanical switch in the second DC power transmission line; a common auxiliary line electrically connected between a second connection point to which the first auxiliary line and the second auxiliary line are electrically connected, and the first connection point (j); a first unit provided in the common auxiliary line; and a second unit provided on each of a first line, the first line being the first DC power transmission line or the first auxiliary line, and a second line, the second line being the second DC power transmission line or the second auxiliary line, characterized in that one of the first unit and the second unit is a semiconductor circuit breaker, the semiconductor circuit breaker including at least one semiconductor switching device and being capable of breaking a current, and the other of the first unit and the second unit is a commutation device configured to commutate a current flowing through the first DC power transmission line or the second DC power transmission line so that the current flows through the semiconductor circuit breaker when a predetermined condition has been satisfied. a first mechanical switch provided in the first DC power transmission line; a second mechanical switch provided in the second DC power transmission line; a first auxiliary line electrically connected to a first position (j3-1) located on the side opposite to the first connection point (j) with respect to the first mechanical switch in the first DC power transmission line; a second auxiliary line electrically connected to a second position (j3-2) located on the side opposite to the first connection point (j) with respect to the second mechanical switch in the second DC power transmission line; a common auxiliary line electrically connected between a second connection point to which the first auxiliary line and the second auxiliary line are electrically connected, and the first connection point (j); a first unit provided in the common auxiliary line; and a second unit provided on each of a first line, the first line being the first DC power transmission line or the first auxiliary line, and a second line, the second line being the second DC power transmission line or the second auxiliary line, characterized in that one of the first unit and the second unit is a semiconductor circuit breaker, the semiconductor circuit breaker including at least one semiconductor switching device and being capable of breaking a current, and the other of the first unit and the second unit is a commutation device configured to commutate a current flowing through the first DC power transmission line or the second DC power transmission line so that the current flows through the semiconductor circuit breaker when a predetermined condition has been satisfied.