A semiconductor module has switching semiconductor elements connected in parallel to each other and at least a free wheeling semiconductor element reversely connected in parallel to the switching semiconductor elements. The free wheeling semiconductor element is placed between the switching semiconductor elements. At both end parts of the semiconductor elements, each of the switching semiconductor elements is placed. A longitudinal side of each of the switching semiconductor elements and the free wheeling semiconductor element is placed in parallel to a short side of the semiconductor module. An electric-power conversion device has a plurality of arms. Each arm is composed of the semiconductor elements.