Patent ID: 7575278

Claim:
A seat back for a vehicular seat comprising: a plate member for supporting a back of a pad; and an elastic support mechanism capable of elastically holding the plate member for moving the plate member forward and backward with respect to a seat back frame, wherein the plate member includes a thoracic vertebra avoiding portion having at least one of an open hole and a recessed portion recessed in a direction away from a thoracic vertebrae of a user seated on the vehicular seat, so as to avoid a pushing force to the thoracic vertebrae, wherein the thoracic vertebra avoiding portion is vertically elongated at a substantially widthwise center position of the plate member and has a width of 40 to 100 mm, wherein the thoracic vertebra avoiding portion includes an upper hole and a lower hole, further wherein the recessed portion is positioned between the upper hole and the lower hole, wherein the elastic support mechanism includes a plurality of elastic bridge members bridged horizontally over the seat back frame, wherein one of the elastic bridge members is longitudinally adjustable and is able to adjust a position of a portion of the plate member in a forward and backward direction, wherein the plate member includes a rib extending horizontally at a lower portion thereof with respect to the thoracic vertebra avoiding portion, and wherein the longitudinally adjustable elastic bridge member is disposed along the rib extending horizontally.