The present invention relates to a direct current (DC) circuit breaker using a magnetic field, for generating a magnetic flux in a direction vertical to the direction of an arc current generated in a main switch so as to increase resistance to the arc current and for continuously supplying a circulating current from a DC line so as to further increase the magnetic flux and thus continuously increase the resistance to the arc current, thereby extinguishing an arc. The DC circuit breaker using a magnetic field according to the present invention comprises: a main switch installed in a DC line; a coil wound so as to generate a magnetic flux in a direction vertical to the direction of an arc current generated when the main switch is opened; a semiconductor switch for switching current application to the coil; a capacitor connected in series to the semiconductor switch; and a first diode for conducting the electric current of the line, supplied from one side of the main switch, to the capacitor, wherein the semiconductor switch is turned on, in case a fault occurs, so that the electric current is applied to the coil by the voltage charged in the capacitor.