A load-supporting structure for a chair includes a receiving surface component provided with a curved receiving surface configured to receive a load from a seated person; a load supporter supporting the receiving surface component from a back side of the receiving surface; and a curved shape-changing portion configured to change a curvature radius of the receiving surface from a curvature radius in an initial state thereof to a greater curvature radius than that in the initial state in accordance with a load received by the receiving surface component. The receiving surface component generates a biasing force for returning the curvature radius of the receiving surface to that in the initial state.