In one embodiment, a method of manufacturing a semiconductor device includes forming a first film on a substrate. The method further includes housing the substrate provided with the first film in a chamber, and introducing a first gas into the chamber. The method further includes generating plasma discharge of the first gas in the chamber or applying radiation to the first gas in the chamber. The method further includes introducing a second gas containing a metal component into the chamber to cause the metal component to infiltrate into the first film after the generation of the plasma discharge or the application of the radiation is started.