A semiconductor device, in which it is possible to maintain high reliability in that interfacial breakdown does not occur between a solder ball and a conductive film, is provided. The semiconductor device according to the present invention comprises an uppermost layer interconnection 101, an insulating film, which is provided above the uppermost layer interconnection 101, provided with a pad via 104 reaching the uppermost layer interconnection 101, and a conductive film, which is connected to the uppermost layer interconnection 101 in a bottom of the pad via 104, and formed across from the bottom of the pad via 104 to outside the pad via 104; wherein the conductive film and the solder ball 108 provided in contact with the insulating film, and an alloy layer 110 containing a metallic element contained in the solder ball 108 and a metallic element contained in the conductive film intervene, and the solder ball is formed so as to cover the alloy layer 110.