Improve the productivity and cost for the manufacturing of a semiconductor device referred to as a wafer level CSP. The manufacturing method for a semiconductor device related to this invention contains each of the processes that form a wiring (18) for the purpose of electrically connecting each electrode pad (10a) and external connecting terminals on top of a wafer (10) on which semiconductor elements are formed, connect conductive balls that are preformed by a separate process on top of this, and next, cover the above-mentioned wafer with a resin (32) such that the upper portion of the conductive supporting posts (30) are exposed. In a later process, solder balls (34) are arranged as external connecting terminals on the upper portion of the conductive supporting posts, and in the final process, semiconductor elements are formed by dicing the above-mentioned wafer along the boundary lines of the above-mentioned semiconductor elements.