A semiconductor device includes: a semiconductor element; a heat sink including a first surface and a second surface, the semiconductor element being joined to the first surface, the second surface being a surface on an opposite side of the first surface; and a package that is in contact with the semiconductor element and the first surface of the heat sink, the package including a recess portion in an outer face, wherein the heat sink includes a thick portion, and a thin portion having a thickness that is smaller than that of the thick portion, and the thin portion is located on a line connecting an outer face of the semiconductor element and the recess portion in a shortest distance.