Nanoparticles are synthesized in various ways, but the thermal plasma method, which is a rapid cooling process from a very high-temperature reaction field, has the potential to produce nanoparticles that cannot be obtained using other methods. In the thermal plasma method, the particle size can be controlled by the cooling rate, and the crystalline phase can be controlled by the type of plasma gas for some materials. It is also possible to synthesize superhard materials such as nitrides and carbides of metals, as well as metal nanoparticles with a core-shell structure. This paper introduces the synthesis of these nanoparticles by thermal plasma method.