A power unit device which can be made small, with which special measures of plant and labor at the time of assembly are unnecessary, and of which assembly is easy and universality in its manufacturing aspect is excellent. The power unit device has a heat sink having a first heat-receiving part and formed on the opposite side from this a second heat-receiving part; a power module, in firm contact with the first heat-receiving part, containing a power semiconductor element for performing DC-AC conversion and/or AC-DC conversion for one phase; a smoothing condenser, in firm contact with the second heat-receiving part, for suppressing ripple current of the power semiconductor element; and fixing means passing through the power module, the heat sink and the smoothing condenser.