To cool a battery device without utilizing an air conditioner of a vehicle.

This battery unit 10 is provided with a battery device 12 for feeding power to a motor 4 for driving the vehicle integrally with a cooling and heating device 13 comprising a compressor 50 to be driven by power fed from the battery device 12, a cooling and heating device side heat exchanger 54 for performing heat exchange with outside air, an expansion valve 56 as a pressure reducing device, and a cooling and heating plate 22 as a heat exchanger for cooling or heating the battery device 12.