SEATBACK OF VEHICLE SEAT

A seatback of a vehicle seat, including: a cushion member including a central section, and a pair of side sections respectively connected to a pair of side edge portions of the central section so as to be rotatable relative to the central section; a lumbar support configured to contact a rear face of the central section and to be deformable such that a front-rear direction position of part of the lumbar support is changed; a covering member having a bag shape and covering the cushion member and the lumbar support; a pair of side restraint members configured so as to be connected to an inner face of the covering member and to respectively restrain the pair of side sections; and a pair of back face restraint members provided at an inner face of a back face configuration section of the covering member and connected to the side restraint members.