The disclosed headrest support device is formed with a synthetic thermoplastic resin material as a base, in an effort to reduce overall weight. The headrest support device is provided to the top of the seatback of a seat for a vehicle, holds a headrest that supports the head of a seat occupant, and is such that the height in the vertical direction of the headrest can be adjusted. The headrest support device is caused to comprise two stay guides (1, 1) into which two headrest stays (81, 81) provided to the headrest (8) couple, and which fulfill the role of holding said two headrest stays (81, 81) at a predetermined position; strip-shaped staying-pressing sections (15, 15) that are a portion of each of the tubular sections (11, 11) forming the stay guides (1, 1) and that are formed at a portion in the axial direction of the tubular sections (11, 11); and holding clips (2, 2) that are provided to the place on the tubular sections containing the staying-pressing sections (15, 15) and that move so as to press said staying-pressing sections (15, 15) towards the inner surface.