There is provided a method for producing a powder mixture containing an alkali metal salt that exhibits basicity in an aqueous solution (component (A)) at least one type of metal salt selected from the salts of copper, manganese, iron, cobalt and zinc (component (B)) and a compound represented by the following general formula (1) (component (C)), including spraying and mixing an aqueous solution of metal which is an aqueous solution of the aforementioned component (B) with a powder of the aforementioned component (A), and then mixing a powder of the aforementioned component (C) therewith. According to the present invention, it is possible to provide a method for producing a powder mixture which can easily produce a powder mixture that exhibits excellent solubility in water even when containing a basic alkali metal salt and a metal salt:
