Abstract: A seat support mechanism including a lifter, and configured to perform a cushion frame suspension function no matter to what height a cushion frame is adjusted. Torsion bars extending in the width direction of a cushion frame and elastically supporting the cushion frame are supported by a link mechanism disposed between sliders and the cushion frame. Even if the attitude of the link mechanism is displaced when the lifter adjusts the height, the positions of the torsion bars are displaced so as to follow the displacement. The torsion bars elastically support the cushion frame no matter to what height the torsion bars are displaced. Thus, no matter to what height the cushion frame is adjusted, the torsion bars are able to support the cushion frame with predetermined elasticity and to exhibit predetermined vibration absorption characteristics.