A method of efficiently and inexpensively fabricating a chip-size package having an electrode pitch expanded by forming a conductor wiring on the electrode forming surface side of a semiconductor chip, especially, a method for facilitating wiring and bump forming. A semiconductor device comprising a semi-conductor elements and conductor wirings formed on the semiconductor elements by etching wiring-forming metal foil; and a fabrication method for a semiconductor device comprising the steps of laminating wiring forming metal foil on the electrode forming surface side on the semiconductor, forming a resist wiring pattern on the metal foil, etching the metal foil, and slicing the device into individual elements.