A semiconductor device includes a semiconductor device layer, a multilayered wiring section formed of a plurality of wiring layers and a plurality of interlayer insulating films on one surface of the semiconductor device layer, an external connection electrode formed on one of the plurality of wiring layers, and an opening formed in a concave shape extending from the semiconductor device layer to the multilayered wiring section so as to expose a surface of the external connection electrode; the opening has a larger opening diameter at an end farther from the external connection electrode than at the other end closer to the external connection electrode.