Abstract: After depositing a metal film on an insulating film on a semiconductor substrate, a first interlayer insulating film is formed on the metal film. After forming first plug openings in the first interlayer insulating film by etching the first interlayer insulating film with a first mask pattern used as a mask, first connection plugs are formed by filling a first conducting film in the first plug openings. A second interlayer insulating film is formed on the first interlayer insulating film. After forming second plug openings respectively on the first connection plugs in the second interlayer insulating film by etching the second interlayer insulating film with a second mask pattern used as a mask, second connection plugs are formed by filling a second conducting film in the second plug openings.