There are provided an electric motor (12) that is driven by an engine (8) to generate electric power or assists in a drive of the engine (8) by supply of electric power thereto, a heat exchanger (13) to which cooling air is supplied by a cooling fan (8A), a heat exchanger upstream room (28) that is positioned upstream of the heat exchanger (13) in a flow direction of the cooling air supplied to the heat exchanger (13), and an electricity storage device (30) that stores or discharges electric power. In addition, a radiator (42) for electricity storage device, a cooling pump (43) for electricity storage device and a cooling line (44) for electricity storage device configure a cooling system (41) for electricity storage device that independently cools the electricity storage device (30) aside from the inverter device (34), and the cooling system (41) for electricity storage device is arranged in the heat exchanger upstream room (28).