Vehicle rear seat backrest unit, vehicle rear seat backrest and vehicle

The invention provides a vehicle rear seat backrest unit, a vehicle rear seat backrest and a vehicle. The vehicle rear seat backrest unit comprises a backrest framework, a locking part and a pivotal connecting portion, wherein the locking part is formed between the backrest framework and a vehicle floor and fixedly locks the backrest framework to the vehicle floor; and the pivotal connecting portion is connected between the side of the backrest framework and the side periphery of the vehicle and is provided with a pivotal joint shaft arranged in the vertical direction of the vehicle so as to form the pivotal center of the backrest framework. According to the vehicle rear seat backrest unit, by arranging the pivotal connecting portion, the effect that a seat pivots around the pivotal joint shaft arranged in the vertical direction of the vehicle can be achieved, the rotation mode of the vehicle rear seat is changed, and the utilization ratio of the interior space of the vehicle is increased; and meanwhile, by m