A voltage-type DC power supply comprising, a voltage step-down chopper having a switching element, an inductor and a first diode and constituting a DC source, an inverter having a bridge circuit including four switching elements; a first switching element to a fourth switching element, being configured to convert DC output from the voltage step-down chopper in single-phase AC power by operating the switching elements, a rectifier configured to perform AC-DC conversion of an output from the inverter, and to supply a direct current thus obtained to a plasma generator of a load, and a short-circuit section between the voltage step-down chopper and the inverter, configured to establish a short-circuit between a positive terminal and a negative terminal of the voltage step-down chopper, the voltage-type DC power supply being characterized by an arc detector configured to detect an arc discharge in the plasma generator of the load, and a controller configured to control the voltage step-down chopper and the inverter, wherein, when the arc discharge occurs, the controller turns off the first to the fourth switching elements in the inverter, turns off the switching element (Q 1) in the voltage step-down chopper, turns on a short-circuit switching element (Q 2) in the short-circuit section, and forms a circulating circuit by the inductor (L F) and the first diode (D 1) in the voltage step-down chopper and the short-circuit switching element (Q 2) in the short-circuit section, and when the arc is extinguished, or after a lapse of a preset time from occurrence of the arc discharge, the controller turns on the first to the fourth switching elements in the inverter, turns on the switching element (Q 1) in the voltage step-down chopper, and turns off the short-circuit switching element (Q 2) in the short-circuit section, thereby supplying the circulating current passing through the circulating circuit, to the inverter. an inverter having a bridge circuit including four switching elements; a first switching element to a fourth switching element, being configured to convert DC output from the voltage step-down chopper in single-phase AC power by operating the switching elements, a rectifier configured to perform AC-DC conversion of an output from the inverter, and to supply a direct current thus obtained to a plasma generator of a load, and a short-circuit section between the voltage step-down chopper and the inverter, configured to establish a short-circuit between a positive terminal and a negative terminal of the voltage step-down chopper, the voltage-type DC power supply being characterized by when the arc discharge occurs, the controller turns off the first to the fourth switching elements in the inverter, turns off the switching element (Q 1) in the voltage step-down chopper, turns on a short-circuit switching element (Q 2) in the short-circuit section, and forms a circulating circuit by the inductor (L F) and the first diode (D 1) in the voltage step-down chopper and the short-circuit switching element (Q 2) in the short-circuit section, and when the arc is extinguished, or after a lapse of a preset time from occurrence of the arc discharge, the controller turns on the first to the fourth switching elements in the inverter, turns on the switching element (Q 1) in the voltage step-down chopper, and turns off the short-circuit switching element (Q 2) in the short-circuit section, thereby supplying the circulating current passing through the circulating circuit, to the inverter.