A load support structure for a chair includes a tensile material on which a load support surface configured to receive a load of a seated person is formed, a pair of support sections (51) to which the tensile material is attached, and which is elastically deformable in response to a force acting from the tensile material, a first reinforcing section (41) which is disposed to be spaced apart from the pair of support sections (51) in a surface perpendicular direction perpendicular to the load support surface, is located on a side opposite to the load support surface, and extends along an extending direction of the support section, and a connecting body which connects each of both end portion sides of the support section (51) with a corresponding end portion side of both end portion sides of the first reinforcing section (41), in which the support sections (51) are disposed outside the first reinforcing section (41) in a view of the surface perpendicular direction from the load support surface side.