A connection via hole is formed in an inter layer insulation film that covers a copper pad. Copper is formed within the connection via hole to form a connection copper via metal. An aluminum pad having a barrier metal thereunder for preventing reaction between copper and aluminum is formed on the connection copper via metal, thereby electrically connecting the copper pad and the aluminum pad to each other through the connection copper via metal. A step formed by the connection via hole that is formed in the inter layer insulation film is made substantially equal to zero with the aid of the connection copper via metal and at the same time, a film thickness of aluminum constituting the aluminum pad is reduced, thereby reducing manufacturing cost of the semiconductor device. Moreover, even when the connection copper via metal directly lying under the aluminum pad is oxidized, oxidation of the copper pad can be prevented, thereby advantageously preventing the breaking of copper interconnects connected to the copper pad and improving reliability of the semiconductor device.