Abstract: In a water-soluble casting mold according to the present invention, after casting sand is obtained by adding a water-soluble binder containing an inorganic sulfate compound such as magnesium sulfate or the like easily solved in water and water to a refractory granular material for casting sand, the casting sand is dried by microwave radiation or the like in such a manner that the inorganic sulfate compound in the binder is kept retaining at least a portion of crystal water and accordingly, since the inorganic sulfate compound exists in hydrate state in the mold, the mold after drying is provided with good water-solubility and a sufficiently high strength as well, thereby it is possible to recover easily and use repeatedly the binder.