A seat comprising a seat frame, the seat frame comprising: a lower frame configured to couple lower portions of side frames arranged on right and left sides, wherein the lower frame includes a back wall portion provided on a back side, a front wall portion provided in front of the back wall portion , and a coupling portion that couples lower ends of the back wall portion and the front wall portion , the back wall portion includes a pair of side portions forming ends in a seat width direction and each side portion of the pair formed along outer shapes of the side frames , and an inclined portion provided between the side portions and inclined such that a lower end of the inclined portion is positioned in front of an upper end of the inclined portion , the inclined portion is provided in front of the side portions , attachment portions to which a pressure receiving member configured to support an occupant is attached, are provided at the front wall portion of the lower frame , characterized in that it further comprises a reinforcing portion provided at an upper edge of the inclined portion , and the reinforcing portion is a flange portion protruding behind the seat. a lower frame configured to couple lower portions of side frames arranged on right and left sides, wherein the lower frame includes a back wall portion provided on a back side, a front wall portion provided in front of the back wall portion , and a coupling portion that couples lower ends of the back wall portion and the front wall portion , a back wall portion provided on a back side, a front wall portion provided in front of the back wall portion , and a coupling portion that couples lower ends of the back wall portion and the front wall portion , the back wall portion includes a pair of side portions forming ends in a seat width direction and each side portion of the pair formed along outer shapes of the side frames , and an inclined portion provided between the side portions and inclined such that a lower end of the inclined portion is positioned in front of an upper end of the inclined portion , the inclined portion is provided in front of the side portions , attachment portions to which a pressure receiving member configured to support an occupant is attached, are provided at the front wall portion of the lower frame , characterized in that it further comprises a reinforcing portion provided at an upper edge of the inclined portion , and the reinforcing portion is a flange portion protruding behind the seat. a pair of side portions forming ends in a seat width direction and each side portion of the pair formed along outer shapes of the side frames , and an inclined portion provided between the side portions and inclined such that a lower end of the inclined portion is positioned in front of an upper end of the inclined portion , the inclined portion is provided in front of the side portions , attachment portions to which a pressure receiving member configured to support an occupant is attached, are provided at the front wall portion of the lower frame , characterized in that it further comprises a reinforcing portion provided at an upper edge of the inclined portion , and the reinforcing portion is a flange portion protruding behind the seat. <EOS>