A power unit includes a plurality of power modules for controlling individual phases of a pair of rotating electric machines and a heat sink on which the power modules are mounted. Each of the power modules includes a metal block, four power electronic semiconductor devices which are heat-generating elements mounted on the metal block with electrically conductive device bonding layers placed in between, and a plastic case. The plastic case is made of a plastic material sealing the power electronic semiconductor devices and the metal block in a single package with leads connected to top- and bottom-side electrodes of the power electronic semiconductor devices extending outward from the plastic case.