A method of manufacturing a semiconductor device includes preparing a substrate having an interlayer insulating film and a hard mask provided on the interlayer insulating film and having a predetermined pattern, etching the interlayer insulating film to form a trench, forming a MnOx film through an ALD method in a state where the hard mask is left on the interlayer insulating film, the MnOx film being turned into a self-forming barrier film by reacting with the interlayer insulating film, performing a hydrogen radical processing on the MnOx film, forming a Ru film through a CVD method, forming a Cu-based film through a PVD method or by forming a Cu seed through the PVD method, and then performing a Cu plating processing so as to embed the Cu-based film within the trench, and performing a CMP method to remove the hard mask and to form a Cu wiring.