A vehicle hub unit that supports a wheel that attaches to a pneumatic tire and is attached to a joint and an air pressure adjusting device that has this vehicle hub unit, provided with a first air passage that is formed with a first opening in at least one location on a surface that attaches to the wheel, is attached to pneumatic piping of the joint that supplies air, and supplies air from the first opening to the wheel; and a second air passage that is formed with a second opening in at least one location on a surface that attaches to the wheel, is attached to pneumatic piping of the joint that exhausts air of the joint, and collects air of the wheel from the second opening.