An object of the invention is to make it possible to perform the embedding of a Cu diffusion preventing film and a Cu film to a fine pattern of a high aspect ratio by using a medium of a supercritical state in a manufacturing process of a semiconductor device. The object of the invention is achieved by a substrate processing method comprising a first step of processing a substrate by supplying a first processing medium containing a first medium of a supercritical state onto the substrate, a second step of forming a Cu diffusion preventing film on the substrate by supplying a second processing medium containing a second medium of a supercritical state onto the substrate, and a third step of forming a Cu film on the substrate by supplying a third processing medium containing a third medium of a supercritical state onto the substrate.