An electric-power converting device having an inverter circuit of a 4-parallel configuration is realized by a combination of four first to third power semiconductor module devices. In each of module device groups, a single unit of the first power semiconductor module device and a single unit of the second power semiconductor module device are mixedly disposed so as to be alternately disposed. Furthermore, the first to third power semiconductor module devices have circuit element groups which have a common point that each circuit element group includes at least one of first and second transistors and first and second diodes.