The present invention relates to a method for manufacturing a natural mineral food raw material and an edible raw material to which deep seawater minerals are added, by adjusting the pH of alkaline water produced by electrolyzing seawater, deep seawater, or condensed seawater, producing a magnesium salt and calcium salt precipitate, and condensing and separating same, and more particularly, to a method for manufacturing a high hardness mineral beverage and a mineral beverage having the magnesium and calcium content adjusted, wherein the method comprises the steps of: pre-treating seawater or deep seawater and then initially passing said seawater through a reverse osmosis (RO) membrane in order to manufacture condensed water and membrane-filtered water electrolyzing the condensed water in order to manufacture acidic water and alkaline water adjusting the amount of current during the manufacture of the alkaline water in order to produce alkaline water having a hydrogen ion concentration (pH) of between 10 and 13 producing the alkaline water having a hydrogen ion concentration of between 10 and 13, producing calcium salt and magnesium salt for each pH level in a precipitation chamber, and precipitating and separating same and mixing the separated calcium salt and magnesium salt and dissolving same in deionized water.
