To solve a problem in which a multi-ply woven fabric excellent in heat-retaining property and bulkiness can not be obtained because a plurality of unit woven fabrics constituting the multi-ply woven fabric are firmly bound by tension of binding yarn and an air layer between superposition of a plurality of woven fabrics becomes few.

The multi-ply woven fabric bound by a binding yarn 3 in a state in which a plurality of woven fabrics (unit woven fabrics 1 and 2) are superposed are chemically treated to reduce an amount of the binding yarn 3. Specifically, a reducible yarn 4 for reducing the amount by chemical treatment is used as the binding yarn 3 and the multi-ply woven fabric is brought into contact with an aqueous solution of caustic soda set under prescribed conditions of concentration and temperature for a prescribed time to carry out reduction treatment of the amount of a reducible yarn 4.