Provided are a method of producing mixed powder comprising noble metal powder and oxide powder, wherein powder of ammonium chloride salt of noble metal and oxide powder are mixed, the mixed powder is subsequently roasted, and ammonium chloride is desorbed by the roasting process in order to obtain mixed powder comprising noble metal powder and oxide powder, and mixed powder comprising noble metal powder and oxide powder, wherein chlorine is less than 1000 ppm, nitrogen is less than 1000 ppm, 90% or more of the grain size of the noble metal powder is 20 μm or less, and 90% or more of the grain size of the oxide powder is 12 μm or less. Redundant processes in the production of noble metal powder are eliminated, and processes are omitted so that the inclusion of chlorine contained in the royal water and nitrogen responsible for hydrazine reduction reaction is eliminated as much as possible. Consequently, the present invention aims to omit the drying process at a high temperature and thereby prevent grain growth and aggregation, and further eliminate the pulverization and classification processes in order to considerably reduce the production cost.