Cold-spray processing typically employs finer and smaller-diameter metal powders than those of the conventional thermal spraying powders. Furthermore, cold-sprayed particles exhibit fewer oxides than thermally sprayed particles due to the absence of particle melting during spraying. For these reasons, it is necessary to give extra attention to dust explosion and dust fire when using the cold spray, for industrial and R&D purposes. The dust explosion properties of metal powders used for the cold spray were examined for the purpose of not only preventing the dust explosions and fires, but also protecting the workers' safety and health. In order to utilize this new technology of cold spray for industrial use, it is necessary to manage the risks based on risk assessment. However, there are few research reports focused on such risk management. Therefore, in this study, the dust explosion properties of aluminum, titanium, zinc and iron based alloy powders were evaluated by JIS Z 8818: "Test method for minimum explosible concentration of combustible dusts", IEC61241-2-3(1994-09) Section3: "Method for determining minimum ignition energy dust/air-mixtures", and JIS Z 8817: "Test method for explosion pressure and rate of pressure rise of combustible dusts". This paper reports on the dust explosion properties of the above-mentioned metal powders.