The purpose of this paper is to prepare nickel particles by arc plasma method with hydrogen addition. The effect of anode jet formation on the nanoparticle production was investigated by high-speed camera observations. The high-speed camera system with appropriate band-pass filters successfully provides the observation of anode jet image without cathode jet image. The areas of the anode jet and the cathode jet were separately estimated from the high-speed images. From these observations, the periodical fluctuation of the anode jet was confirmed. Higher hydrogen concentration leads to larger anode jet area, resulting from the enhanced evaporation of the anode material.