Provided is a semiconductor device having excellent moisture resistance and excellent high-temperature storage characteristics. The semiconductor device comprises a lead frame having a die pad section and an inner lead section, as a substrate, and has: a semiconductor element mounted on the die pad section; an electrode pad provided in the semiconductor element; a copper wire connecting the inner lead section and the electrode pad, provided on the substrate; and a sealing resin that seals the semiconductor element and the copper wire. An area of the electrode pad at least within the range of no more than 3[mu]m from the joining surface of the copper wire, in the depth direction, includes as the main component thereof a metal having a smaller ionization tendency than aluminum; and the sulfur content in the copper wire is 15-100 ppm relative to the copper wire overall.