A method of manufacturing a semiconductor device capable of minimally preventing the property deterioration caused by the oxidation of a metal film, and a substrate processing apparatus are provided. The method of manufacturing a semiconductor device includes: (a) loading a substrate into a processing container; (b) forming a metal film on the substrate using a chemical deposition method by supplying a processing gas into the processing container and exhausting the processing gas; (c) forming an aluminum nitride film on the metal film using the chemical deposition method by supplying an aluminum-containing source gas and a nitrogen-containing gas into the processing container and exhausting the aluminum-containing source gas and the nitrogen-containing gas; and (d) unloading the substrate from the processing container after forming the metal film and the aluminum nitride film, wherein the step (b) and the step (c) are continuously performed while maintaining an inside of the processing container to have an oxygen-free atmosphere.