The semiconductor device includes: a substrate; an electric fuse that includes a lower-layer wiring formed on the substrate, a first via provided on the lower-layer wiring and connected to the lower-layer wiring, and an upper-layer wiring provided on the first via and connected to the first via, a flowing-out portion of a conductive material constituting the electric fuse being formed in a cut-off state of the electric fuse; and a heat diffusion portion that includes a heat diffusion wiring that is formed in the same layer as one of the upper-layer wiring and the lower-layer wiring and is placed on a side of the one of the upper-layer wiring and the lower-layer wiring, the heat diffusion portion being electrically connected to the one of the upper-layer wiring and the lower-layer wiring.