A seat for a vehicle, said seat comprising: - a frame intended to be mounted on a floor of the vehicle, - a seat cushion, - an adjustment and suspension device comprising a base fixed to the frame and a supporting plate fixed to a lower surface of the seat cushion, the supporting plate being mounted movable in translation relative to the base in a direction of elevation, - a restraint system restraining the supporting plate of the adjustment and suspension device on the frame, the restraint system comprising: - at least one restraint member fixed to the frame, the restraint member defining at least one through opening extending along a main direction of elongation parallel to the direction of elevation, - at least one restraint element fixed to the supporting plate, the through opening of the restraint member receiving the restraint element free in translation along the main direction of elongation, the through opening being capable of restraining said restraint element along a restraint direction perpendicular to the vertical direction in the event of vehicle impact, characterized in that the frame comprises a front section and a rear section each mainly extending along a direction parallel to the transverse direction and two side sections connecting the front and rear sections and each mainly extending along a direction parallel to the longitudinal direction, each of the front section, rear section and side sections respectively comprising an inner front wall, an inner rear wall and two inner side walls defining between them a central housing receiving the adjustment and suspension device. - a frame intended to be mounted on a floor of the vehicle, - a seat cushion, - an adjustment and suspension device comprising a base fixed to the frame and a supporting plate fixed to a lower surface of the seat cushion, the supporting plate being mounted movable in translation relative to the base in a direction of elevation, - a restraint system restraining the supporting plate of the adjustment and suspension device on the frame, the restraint system comprising: - at least one restraint member fixed to the frame, the restraint member defining at least one through opening extending along a main direction of elongation parallel to the direction of elevation, - at least one restraint element fixed to the supporting plate, the through opening of the restraint member receiving the restraint element free in translation along the main direction of elongation, the through opening being capable of restraining said restraint element along a restraint direction perpendicular to the vertical direction in the event of vehicle impact, characterized in that the frame comprises a front section and a rear section each mainly extending along a direction parallel to the transverse direction and two side sections connecting the front and rear sections and each mainly extending along a direction parallel to the longitudinal direction, each of the front section, rear section and side sections respectively comprising an inner front wall, an inner rear wall and two inner side walls defining between them a central housing receiving the adjustment and suspension device. - at least one restraint member fixed to the frame, the restraint member defining at least one through opening extending along a main direction of elongation parallel to the direction of elevation, - at least one restraint element fixed to the supporting plate, the through opening of the restraint member receiving the restraint element free in translation along the main direction of elongation, the through opening being capable of restraining said restraint element along a restraint direction perpendicular to the vertical direction in the event of vehicle impact, characterized in that the frame comprises a front section and a rear section each mainly extending along a direction parallel to the transverse direction and two side sections connecting the front and rear sections and each mainly extending along a direction parallel to the longitudinal direction, each of the front section, rear section and side sections respectively comprising an inner front wall, an inner rear wall and two inner side walls defining between them a central housing receiving the adjustment and suspension device.