1. A welding stability apparatus for pulsed-arc welding, characterized in that, in consumable electrode gas-shielded pulsed-arc welding, wherein a welding voltage is applied between a welding electrode and a workpiece to be welded, for repeatedly supplying a pulse current and a base current, in alternation, and wherein welding is effected by causing a droplet from the welding electrode to be dropped onto the workpiece for each pulse, it comprises: a detector means for detecting at least one of welding voltage between the welding electrode and the workpiece, welding current flowing between the welding electrode and the workpiece, and power-on time; a computer means for computing degree of irregularity of values detected by the detector means; and an assessment means for comparing the computed irregularity with the irregularity of a known-good pulsed arc at the start of welding, and, from the amount of separation therebetween, assessing the pulsed arc welding stability at the start of welding.