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 (70A, 70B) forming ends in a seat width direction and each side portion (70A, 70B) of the pair formed along outer shapes of the side frames, and an inclined portion provided between the side portions (70A, 70B) 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 (70A, 70B), 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 (70A, 70B) forming ends in a seat width direction and each side portion (70A, 70B) of the pair formed along outer shapes of the side frames, and an inclined portion provided between the side portions (70A, 70B) 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 (70A, 70B), 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 (70A, 70B) forming ends in a seat width direction and each side portion (70A, 70B) of the pair formed along outer shapes of the side frames, and an inclined portion provided between the side portions (70A, 70B) 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 (70A, 70B), 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.