Seat support mechanism, seat structure and suspension seat

According to the present invention, a cushion frame exhibits a suspension function even when the cushion frame is adjusted to any height while a lifter is attached thereto. Torsion bars 330, 340, which are disposed across a cushion frame 10 in the widthwise direction of the cushion frame 10 and which elastically support the cushion frame 10, are supported by a link mechanism 40 which is disposed between a slider 20 and the cushion frame 10. Even when the posture of the link mechanism 40 is displaced by a height adjustment of the lifter 30, the positions of the torsion bars 330, 340 are displaced accordingly. Even when the torsion bars 330, 340 are displaced to any height, there is no change in the elastically supporting of the cushion frame 10 by the torsion bars 330, 340. Therefore, the torsion bars 330, 340 can support the cushion frame 10 with a predetermined elasticity and can exhibit a predetermined vibration absorption characteristic, regardless of the height to which the torsion bars are adjusted.