Provided is a semiconductor module wherein a stress relaxing layer is arranged between a ceramic substrate, upon which semiconductor elements are mounted, and a cooling device on the rear side of the ceramic substrate; and the ceramic substrate, the cooling device and the stress relaxing layer are integrally formed. Furthermore, the stress relaxing layer is separated into a plurality of separated sections by two slits. Furthermore, the slits are positioned between the semiconductor elements when viewed from the thickness direction of the stress relaxing layer and not in a projection region of the semiconductor element.