An inventive semiconductor device includes: a semiconductor chip; an internal pad provided on a surface of the semiconductor chip for electrical connection; a surface protective film covering the surface of the semiconductor chip and having a pad opening from which the internal pad is exposed; a stress relief layer provided on the surface protective film and having an opening portion through which the internal pad exposed from the pad opening is exposed; a connection pad including an anchor buried in the pad opening and the opening portion and connected to the internal pad, and a projection provided integrally with the anchor as projecting on the stress relief layer, the projection having a width greater than an opening width of the opening portion; and a metal ball provided for external electrical connection as covering the projection of the connection pad.