To clarify the cooking losses of minerals (sodium, potassium, phosphorus, calcium, magnesium, iron, zinc, manganese, copper), various food materials were analyzed before and after cooking, and the following results were obtained. (1) The mineral contents of cooked foods in mass cooking were on an average about 60-70 percent of those in raw or uncooked foods. (2) Cooking losses were particularly high in minerals of vegetables. (3) Among various cooking methods, loss of mineral was largest in squeezing after boil and in soaking in water after thin slice, followed by parching, frying and stewing. (4) Cooking losses of minerals in meals cooked in home brought about the similar results as those by the mass cooking procedures. (5) The measures to prevent cooking loss are (a) eating the boiled food with the soup, (b) addition of small amount of salt (about 1% NaCl) in boiling, (c) avoidance of too much boiling, (d) selection of a cooking method causing less mineral loss (stewing, frying or parching).