In some aspects of the invention, multiple insulating substrates each mounting thereon at least one each of at least four semiconductor devices that form at least one of three-level electric power inverter circuits and a base plate on the one surface of which a plurality of the insulating plates are arranged are provided. On the one surface of the base plate, at least four regions are established and multiple insulating substrates are arranged to be distributed so that at least one each of the at least four semiconductor devices is arranged in each of the four regions established on the base plate. This can make the semiconductor devices arranged to be distributed so that heat generating sections determined according to the operation mode of the semiconductor system comes to be partial to disperse generated heat, by which a semiconductor system is provided which can enhance heat dispersion efficiency.