Abstract: The vehicle seat comprising a seat-bottom frame; a seatback frame comprising at least one first lateral riser mounted pivoting relative to said seat-bottom frame around a transverse axis; a first discontinuous type hinge mechanism with a first side-plate rigidly fixed to the seat-bottom frame and a second side-plate; an intermediate riser mounted on the seat bottom frame, pivoting around the transverse axis, by means of the first hinge mechanism where the intermediate riser and the second side-plate are securely connected in rotation around the transverse axis; where the intermediate riser is fixed to the first lateral riser at a distance from the transverse axis; where the intermediate riser has a stiffness less than the stiffness of the first lateral riser of the seatback frame.