US Patent 11007911 Seat back structure

A seat back structure includes, a seat back frame which includes a panel material and a frame material joined with the panel material; a side frame which is included in the frame material and which is positioned in at least one edge side in a width direction of the panel material; and a first vulnerable portion which is formed in the side frame and which deforms when a load from an impact is applied. The first vulnerable portion is a slit formed by cutting out the side frame in a horizontal direction.