In a vehicle differential unit according to an embodiment of the invention, a planetary carrier that is a rotatable member that rotatably supports planetary gears is formed of cylindrical members that are unable to rotate relative to each other on the rotational axis of a pair of output shafts. The vehicle differential unit has a thrust force generation portion that receives a driving force from a drive source of a vehicle and generates a thrust force along the direction of the rotational axis of the pair of output shafts, and a relative movement limiting portion that limits a relative movement between the cylindrical members along the axial direction due to the thrust force when the vehicle is in the drive mode.