A method for easily making an ice slab serving as the foundation of an artificial snow skiing field and artificial snow whose upper layer is powdery by flooding aqueous slurry made by adding water to granular wet water absorbent polymer on a slope of a natural skiing field or a slant or horizontal surface of a natural skiing field or indoor artificial snow skiing field equipped with a cooling system, obtaining the deposit layer of the granular wet water absorbent polymer in which water is separated from the slurry and freezing the deposit layer.