The present invention provides a method for forming a semiconductor device, which comprises the steps of preparing a semiconductor wafer including an electrode pad, an insulating film formed with a through hole and a bedding metal layer which are formed in a semiconductor substrate, forming a first resist mask which exposes each area for forming a redistribution wiring, over the bedding metal layer, forming a redistribution wiring connected to the electrode pad and extending in an electrode forming area for a post electrode with the first resist mask as a mask, removing the first resist mask by a dissolving solution to expose each area excluding the electrode forming area for the redistribution wiring and forming a second resist mask disposed with being separated from each side surface of the redistribution wiring, forming a redistribution wiring protective metal film over upper and side surfaces of the exposed redistribution wiring with the second resist mask as a mask, removing the second resist mask by a dissolving solution, attaching a dry film over the semiconductor wafer and exposing the electrode forming area lying over the redistribution wiring, forming a post electrode in the electrode forming area with the dry film as a mask, removing the dry film by a removal solvent, and removing the redistribution wiring protective metal film after the removal of the dry film.