A semiconductor device includes a first wiring comprising a first conductive material on a semiconductor layer, a second wiring comprising the first conductive material on the semiconductor layer, a third wiring comprising a second conductive material different from the first conductive material, and an insulation film on the semiconductor layer between the first wiring and the second wiring and between the second wiring and the third wiring. The second wiring is provided on at least two sides of the third wiring, and a mean free path of free electrons in the first conductive material is shorter than a mean free path of free electrons in the second conductive material, or the first conductive material shows quantized conduction and the second conductive material does not show quantized conduction. The first wiring, the second wiring, the third wiring, and the insulation film are in one wiring layer provided on the semiconductor layer.