A semiconductor device includes a semiconductor substrate, an oxygen-containing insulating film disposed above the above-described semiconductor substrate, a concave portion disposed in the above-described insulating film, a copper-containing first film disposed on an inner wall of the above-described concave portion, a copper-containing second film disposed above the above-described first film and filled in the above-described concave portion, and a manganese-containing oxide layer disposed between the above-described first film and the above-described second film. Furthermore, a copper interconnection is formed on the above-described structure by an electroplating method and, subsequently, a short-time heat treatment is conducted at a temperature of 80° C. to 120° C.