To burden each three-phase AC generation winding for welding with a equal load.

The control circuit for a welding current is constituted by equipping with full-wave rectification circuits 12-1, 12-2 and 12-3 with thyristors mixed performing respectively the full-wave rectification of three-phase AC voltage for each three-phase AC generation windings 8-1, 8-2 and 8-3 for welding, series circuits of resistors 13 and capacitors 14, a welding output circuit with each output of the full-wave rectification circuits 12-1, 12-2 and 12-3 with thyristors mixed connected in parallel, a current transformer 15 detecting a welding current made to flow in one phase, a phase control signal generation circuit generating a phase control signal according to a welding current for each generated voltage of each phase of the three-phase AC generation windings 8-1, 8-2 and 8-3 for welding, in which the welding currents is detected, and an ignition circuit 20 igniting respectively simultaneously the thyristors corresponding to each same phase of the full-wave rectification circuits 12-1, 12-2 and 1-3 with thyristors mixed.