To provide a manufacturing method of a semiconductor device which reliably allows connection terminals of each semiconductor package substrate to be soldered and connected to each other and dramatically improves electric connection reliability when a pop structure is formed by connecting the semiconductor package substrates to each other, and to provide the semiconductor device.

In a semiconductor device 1, an upper end part of each solder ball 5 exposed from each via 6 of a mold resin layer 7 is maintained in a clean state in which resin residues of the mold resin layer 7 or the like do not remain during etching removal of a copper support plate 10. This state improves wettability of each solder ball 5 and enables each solder ball 5 to be securely connected to each solder ball 14 of a package substrate 13. Further, the state dramatically improves electric connection reliability between the semiconductor device 1 and the package substrate 13.