To provide a headrest support device, wherein a headrest is operated softly, locked completely at stop, further fixed by a single action in a required angle and position, and wherein the headrest moves smoothly in the direction of approaching to or departing from a back-rest, upward and downward.

A connecting axis 2 supported by an axis supporting part 1 fixed to the back-rest is coupled into one of connecting holes at both ends of an angle adjusting part 3. The part 3 is provided with a slit 6 connecting the connecting holes 4 and 5 at both ends; a pressurizing means such as a hydraulic cylinder 7 permits the slit 6 to narrow under pressure. Into the other connecting hole of the part 3, a cylinder part 12, which has a slit 11 at one end of a first connecting 10, is coupled. A connecting axis 14 of a second connecting rod 13 is coupled into the part 12. One end of a third connecting rod 15 is connected with the other end of the rod 10. The other ends of the rods 13, 15 are connected with the back surface of the head rest 17 which has a switch 18.