Abstract: Provided is a fabric having a ground weave to which a hygroscopic polymer is fixed, and the fabric generates heat under moisture absorbing conditions and provides a more comfortable feeling to a person by temperature drop in moisture desorption conditions. A fiber structure is prepared by fixing a hygroscopic polymer to fibers of the fabric, and the front layer on the front surface side and the back layer on the back surface side have different fiber densities where the boundary between the front layer and the back layer is on the center line of a cross section of the fiber structure.