There are disclosed a novel desiccant containing anhydrous maltose and dehydration of hydrous matters, e.g. food, pharmaceutical and cosmetic, therewith. Such hydrous matters are dehydrated without causing alteration or deterioration by incorporating anhydrous maltose into the hydrous matters to convert the anhydrous maltose into crystalline beta-maltose hydrate. The anhydrous maltoses usable in the invention are anhydrous crystalline alpha-maltose, anhydrous crystalline beta-maltose and anhydrous amorphous beta-maltose, specifically, those in pulverulent form.