A vehicle seat comprising a back and a seat proper which includes a rigid frame supported by a raising mechanism for moving the seat upwards or downwards, the raising mechanism being controlled by an actuator which comprises a tube provided with a nut and a screw which co-operates with the nut, the screw being provided with a free end situated inside the tube, the raising mechanism further comprising an elastically-deformable member for assisting the motor of the actuator. The elastically-deformable member is housed inside the tube of the actuator between the free end of the screw and a support element secured to the actuator tube.