A method for manufacturing metal powder by melting at least a portion of a metal starting material using a plasma (7) inside a reaction vessel (2) to form molten metal (8), then evaporating the molten metal (8) to generate a metal vapor, transferring the metal vapor together with a carrier gas supplied into the reaction vessel (2) from the reaction vessel (2) to a cooling pipe (3), and cooling and coagulating to generate the metal powder, wherein oxygen gas is supplied into the reaction vessel (2).