Provided is a semiconductor device. The semiconductor device includes a semiconductor substrate having a contact region. An interlayer insulating layer is disposed on the semiconductor substrate. A lower contact plug passing through the interlayer insulating layer and electrically connected to the contact region is disposed. An interconnection structure is disposed on the interlayer insulating layer. An adjacent interconnection spaced apart from the interconnection structure is disposed on the interlayer insulating layer. A bottom surface of the interconnection structure includes a first part overlapping a part of an upper surface of the lower contact plug, and a second part overlapping the interlayer insulating layer.