Provided is a circuit breaker for a DC current using a magnetic field, which generates a magnetic flux and extinguishes an arc current generated in a main switch. The circuit breaker includes 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 DC 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.