A semiconductor device includes: a first interconnection line and a second interconnection line which extend apart from each other on a first plane at a first level on a substrate; a bypass interconnection line that extends on a second plane at a second level on the substrate; and a plurality of contact plugs for connecting the bypass interconnection line to the first interconnection line and the second interconnection line. A method includes forming a bypass interconnection line spaced apart from a substrate and forming on a same plane a plurality of interconnection lines connected to the bypass interconnection line via a plurality of contact plugs.