A welding power supply device comprising: an inverter circuit that converts DC power into AC power and outputs the AC power to a welding load; and a voltage superimposing circuit that superimposes a restriking voltage on an output to the welding load when a polarity of an output current of the inverter circuit switches, wherein the voltage superimposing circuit includes: a restriking capacitor to be charged with the restriking voltage; a charging circuit that charges the restriking capacitor with the restriking voltage; and a discharging circuit that discharges the restriking voltage charged in the restriking capacitor, wherein the charging circuit includes: a DC power supply that outputs DC voltage; and characterised in that the charging circuit further includes: a voltage booster that boosts a DC voltage of the DC power supply, wherein the charging circuit charges the restriking capacitor in a first state and a second state following the first state, the first state being a state in which the DC voltage of the DC power supply is directly applied to the restriking capacitor, the second state being a state in which the DC voltage boosted by the voltage booster is applied to the restriking capacitor. an inverter circuit that converts DC power into AC power and outputs the AC power to a welding load; and a voltage superimposing circuit that superimposes a restriking voltage on an output to the welding load when a polarity of an output current of the inverter circuit switches, wherein the voltage superimposing circuit includes: a restriking capacitor to be charged with the restriking voltage; a charging circuit that charges the restriking capacitor with the restriking voltage; and a discharging circuit that discharges the restriking voltage charged in the restriking capacitor, wherein the charging circuit includes: a DC power supply that outputs DC voltage; and characterised in that the charging circuit further includes: a voltage booster that boosts a DC voltage of the DC power supply, wherein the charging circuit charges the restriking capacitor in a first state and a second state following the first state, the first state being a state in which the DC voltage of the DC power supply is directly applied to the restriking capacitor, the second state being a state in which the DC voltage boosted by the voltage booster is applied to the restriking capacitor. a restriking capacitor to be charged with the restriking voltage; a charging circuit that charges the restriking capacitor with the restriking voltage; and a discharging circuit that discharges the restriking voltage charged in the restriking capacitor, wherein the charging circuit includes: a DC power supply that outputs DC voltage; and characterised in that the charging circuit further includes: a voltage booster that boosts a DC voltage of the DC power supply, wherein the charging circuit charges the restriking capacitor in a first state and a second state following the first state, the first state being a state in which the DC voltage of the DC power supply is directly applied to the restriking capacitor, the second state being a state in which the DC voltage boosted by the voltage booster is applied to the restriking capacitor. a voltage booster that boosts a DC voltage of the DC power supply, wherein the charging circuit charges the restriking capacitor in a first state and a second state following the first state, the first state being a state in which the DC voltage of the DC power supply is directly applied to the restriking capacitor, the second state being a state in which the DC voltage boosted by the voltage booster is applied to the restriking capacitor.