PURPOSE: To maintain excellent appearance quality even when a seatback cover is deeply suspended in.

CONSTITUTION: Suspension cotton cloth 40 is sewn in the back face of a seatback cover 38, and a suspend-in fasten rubber 44 is inserted in its inner side. The upper side of the fasten rubber 44 is locked on an upper shape hold wire 22 by an upper end ring 46 and the like, and the lower side of the fasten rubber is locked on the link section 26B of a lower shape hold wire 26 by a joint section 48 and the like. In this place, the lower side of the fasten rubber 44 makes the side end section of the link section 26B in the projected direction a wind-up point, and makes the side end section of the link section 26B in the direction opposite to the projected direction a locking point, even if the fasten rubber 44 is strongly pulled out by an operator to deeply suspend the suspension cotton cloth 40 in, neither the lower end section of a seatback pad is deformed nor the lower end section of a seatback cover is wrinkled. Therefore, excellent appearance quality can thereby be maintained.