Abstract: A headrest of the type inclinable fore-and-aft with respect to a headrest stay upon a seat, which includes a trim cover assembly having an opening formed at one side thereof, and includes an inclination mechanism connected to the headrest stay within the trim cover assembly. In forming the headrest, an inner sealing enclosure element is provided in the interior of trim cover assembly to accommodate those inclination mechanism and headrest stay therein, with a free part of the headrest stay projecting outwardly through a hole of the inner sealing enclosure element, while one the other hand, an outer sealing element is securely engaged with that inner sealing enclosure element so as to close both opening of the trim cover assembly and hole of the inner sealing enclosure element. This closing and sealing effect is made positive by a particular male and female sealing engagement arrangement defined between the inner sealing enclosure element and outer sealing element.