An interconnection structure includes a lower interconnection layer formed on a substrate and composed of a copper layer, an interlayer insulating layer formed on the lower interconnection layer and having a via reaching the lower interconnection layer, an upper interconnection layer electrically connected to the lower interconnection layer through the via, and composed of a copper layer formed in the interlayer insulating layer, and a barrier metal layer formed between the upper interconnection layer and the interlayer insulating layer. The barrier metal layer has an opening in a bottom portion of the via, and through that opening, the upper interconnection layer comes in direct contact with the lower interconnection layer in the bottom portion of the via. Thus, an interconnection structure suppressing concentration of voids in an interconnection under a via due to stress migration can be attained.