Abstract: A seat cushion comprises a cushion body portion including a storage recess and a cushion bottom portion covering the storage recess so as to selectively open or close it. A supplementary seat comprises a supplementary seat back which is pivotally supported so as to rotate in the longitudinal direction and a supplementary seat cushion formed separately from the supplementary seat back. The supplementary seat cushion is configured so as to selectively take a sitting position, where it is located at the side of the seat cushion, and a stored position, where it is stored in the storage recess. Accordingly, since only the supplementary seat cushion is stored in the storage recess, the deterioration of comfortable ride caused by the high-sitting point can be suppressed. Also, the supplementary seat back can be used as a armrest or the like.

Abstract: A seat cushion comprises a cushion body portion including a storage recess and a cushion bottom portion covering the storage recess so as to selectively open or close it. A supplementary seat comprises a supplementary seat back which is pivotally supported so as to rotate in the longitudinal direction and a supplementary seat cushion formed separately from the supplementary seat back. The supplementary seat cushion is configured so as to selectively take a sitting position, where it is located at the side of the seat cushion, and a stored position, where it is stored in the storage recess.