A non-consumable electrode arc-welding method is provided for causing a welding machine to output or stop a welding current in accordance with at least an ON state and an OFF state of a start signal. In the method, a start signal is switched between an ON state and an OFF state, thereby controlling the on/off operation of the welding machine. Further, an operation mode instruction signal is switched between a normal mode and an interval mode, thereby controlling the operation mode of the welding machine. When the operation mode instruction signal indicates the interval mode and also the start signal is in the ON state, the welding current is outputted in a welding current output period. Then, the output of the welding current is suspended in a welding current interval period successively following the welding current output period.