A welding apparatus, comprising: a welding machine comprising: a lower arm member extending substantially in a horizontal direction and comprising an electrode arranged at a distal end side of the lower arm member; and an upper arm member extending substantially in the horizontal direction and comprising an electrode arranged at a distal end side of the upper arm member, the welding machine being configured to cause any one or both of the electrodes (10, 11) to advance and retreat; a robot device to which the welding machine is mounted; the welding apparatus being characterized by comprising: a support member comprising: a vertical member arranged substantially in a vertical direction; and a horizontal member arranged substantially in the horizontal direction, the vertical member being mounted on one of the lower arm member and the upper arm member at a position away from the electrode (10, 11) of the one of the lower arm member and the upper arm member; and a parts-feeding device mounted to the horizontal member and configured to, in use, feed parts to be welded to a steel plate workpiece to the electrode (10, 11) of the one of the lower arm member and the upper arm wherein the vertical member is mounted to the one of the lower arm member and the upper arm member such that the vertical member is adjustable in position in the vertical direction, and wherein the parts-feeding device is mounted to the horizontal member such that the parts-feeding device is adjustable in position in the horizontal direction. a welding machine comprising: a lower arm member extending substantially in a horizontal direction and comprising an electrode arranged at a distal end side of the lower arm member; and an upper arm member extending substantially in the horizontal direction and comprising an electrode arranged at a distal end side of the upper arm member, the welding machine being configured to cause any one or both of the electrodes (10, 11) to advance and retreat; a lower arm member extending substantially in a horizontal direction and comprising an electrode arranged at a distal end side of the lower arm member; and an upper arm member extending substantially in the horizontal direction and comprising an electrode arranged at a distal end side of the upper arm member, the welding machine being configured to cause any one or both of the electrodes (10, 11) to advance and retreat; a robot device to which the welding machine is mounted; a support member comprising: a vertical member arranged substantially in a vertical direction; and a horizontal member arranged substantially in the horizontal direction, the vertical member being mounted on one of the lower arm member and the upper arm member at a position away from the electrode (10, 11) of the one of the lower arm member and the upper arm member; and a vertical member arranged substantially in a vertical direction; and a horizontal member arranged substantially in the horizontal direction, the vertical member being mounted on one of the lower arm member and the upper arm member at a position away from the electrode (10, 11) of the one of the lower arm member and the upper arm member; and a parts-feeding device mounted to the horizontal member and configured to, in use, feed parts to be welded to a steel plate workpiece to the electrode (10, 11) of the one of the lower arm member and the upper arm wherein the vertical member is mounted to the one of the lower arm member and the upper arm member such that the vertical member is adjustable in position in the vertical direction, and wherein the parts-feeding device is mounted to the horizontal member such that the parts-feeding device is adjustable in position in the horizontal direction.