PURPOSE: To improve the resistance to wear, corrosion and heat and to apply composite coating without the coating film being peeled by depositing a first metal on an article in a reaction chamber, then coating the first metal with a second metal and diffusing the metals in both coating films.

CONSTITUTION: The powder of anhydrous chromous chloride and a gaseous mixture of argon and hydrogen are supplied into the reaction chamber 6 from a first coating material feeder 28 to deposit chromium on the surface of an article 10. Chromium carbide is simultaneously formed with the carbon contained in the article 10. The powder of titanium tetrachloride and the gaseous mixture are supplied into the chamber 10 from a second coating material feeder 30 to deposit titanium on the chromium and chromium carbide. The chamber 10 is kept under these conditions for a specified time, the first metal from the first coating film is diffused into the surface of the article 10, and the second metal is diffused into the coating film of the first metal from the second coating film.