A semiconductor module includes a metal core layer that includes: a first metal layer and a second metal layer on the first metal layer, wherein a portion of the second metal layer is removed to expose a surface of the first metal layer, the removed portion of the second metal layer defining a cavity in the metal core layer having the exposed surface of the first metal layer as a bottom surface, and at least one of a side wall and the bottom surface of the cavity has a smoother surface profile than a surface of the first metal layer that is not exposed by the cavity and under the second metal layer; and a semiconductor element provided in the cavity, affixed to the bottom surface of the cavity with a fixing material containing a resin component.