A pulsed wire discharge (PWD) apparatus for mass production of nanosized powders was developed. The apparatus had a wire feeder, and could prepare 1.5 g of Cu powder in 200 sec. The mean surface diameter of Cu powder was 86 nm. The particle size distribution of the powder prepared by 100 discharges was increased than that by one discharge. In addition, the median diameter of the powder after the 100 discharges was larger than that by one discharge. A part of the nanosized powders in production chamber of the apparatus would be grown by the deposition of plasma or vapor formed by the next discharge.