A semiconductor device includes: a substrate extending in a first direction and a second direction intersecting with the first direction; a plurality of input/output pads disposed at one side of the substrate; a first circuit adjacent to the input/output pads in the first direction; a second circuit disposed to be spaced farther apart from the input/output pads in the first direction than the first circuit; a first memory cell array overlapping the first circuit; a second memory cell array overlapping the second circuit; first metal source patterns overlapping the first memory cell array and being spaced apart from each other in the second direction; and a second metal source pattern overlapping the second memory cell array and formed to have a width wider than a width of each of the first metal source patterns in the second direction.