Patent ID: 7731294

Claim:
A seat comprising: a sitting portion frame; a cushion material including a lower layer portion stretched in a front-rear direction on the sitting portion frame, and a surface layer portion layered on the lower layer portion and stretched on the sitting portion frame; and a tension adjusting mechanism that connects connection positions of the lower layer portion in to portions of the sitting frame that are lower than the connection positions, the connection positions being provided on the lower layer portion at locations corresponding to locations where ischial tuberosities of a person are located when the person is seated in the seat; wherein: the tension adjusting mechanism generates tensile force at a time when the person sits in the seat; the surface layer portion includes portions between a central portion in a left-right direction which support the seated person and both end portions in the left-right direction, and which elongate in a left-right direction more easily than the central portion and the both end portions; and the portions between the central portion in the left-right direction and both end portions in the left-right direction include elastic members which elongate more easily than the central portion and the both end portions.