Abstract: A vehicle seat is provided comprising a seat back frame having right and left side frames, a headrest for supporting a head of a seat occupant, and a back-and-forth movable plate member provided inside a backrest that is positioned at a rear of the seat occupant, wherein a backward movement of the plate reduces a distance between the head of the seat occupant and the headrest. The plate is attached to each side frame through a link member and a link support shaft swingably supports the link member. A bracket member that supports the link support shaft and is attached to the side frame.

Abstract: A backrest frame is provided with a cushion plate of one substantially square plate form positioned behind the waist from the upper part of the back of a vehicle seat occupant, movably back and forth by way of a plurality of upper and lower parallel seat springs, one end of either one of a pair of right and left seat springs of the plurality of upper and lower parallel seat springs is connected to a pair of lower link mechanisms provided rotatably on the backrest frame, and a rear end collision sensor is formed by the cushion plate between the seat springs for moving a headrest forward, and a coupling part of the other end of the seat spring is directly attached to the lower link mechanism.