An automotive seat-back structure is provided to protect a passenger's neck vertebra at a vehicle's rear-end collision and also support the passenger's lumbar vertebra. The automotive seat-back structure includes a seat-back frame 2, an actuating member 4 and supporting means 7. A first supporting member 5 is carried by a lower end 2c of the seat-back frame 2, while a second supporting member 6 is carried by the actuating member 4 or the supporting means 7. The first and second supporting members 5, 6 carry a lumbar supporting member 8 capable of supporting the passenger's lumbar vertebra on pressure. The member 8 is carried so as to be rotatable back and forth and also movable up and down.