A semiconductor device according to the present embodiment comprises a first metallic line. The first metallic line is provided above a substrate and extends in a first direction with a first width. At least one second metallic line is connected to the first metallic line and extends in a second direction from the first metallic line with a second width that is smaller than the first width. A dummy metallic line is arranged adjacently to the at least one second metallic line, connected to the first metallic line, and extends in the second direction from the first metallic line. The dummy metallic line is not electrically connected to lines other than the first metallic line.