An assist power-generating motor (12) generates electric power as a result of being driven by an engine (8) or assists the drive of the engine (8) by means of electric power supplied from a power storage device (25). A rotating electric motor (29) is driven by the electric power supplied from the power storage device (25) or supplies to the power storage device (25) regenerated electric power that is generated by a regeneration operation. The assist power-generating motor (12) is controlled by a first inverter (46). The rotating electric motor (29) is controlled by a second inverter (55). The first inverter (46) and the second inverter (55) are attached to a support bracket (37) that is elastically supported upon a rotating frame (5) at a position that is different from the position where the power storage device (25) is attached.
