PURPOSE: To obtain a food raw material capable of immediately heat-processing and serving for eating, by subjecting a food raw material immersed in water to microwave heating and cooling and drying the heated food under vacuum or reduced pressure.

CONSTITUTION: A food raw material such as rice, adzuki bean, soybean or the like is rinsed and washed and then immersed in water for about 30minW1hr. Then the food raw material is charged into a vessel and irradiated with micro waves for several seconds W several minutes to heat the raw material and cooled and dried in vacuum or reduced pressure atmosphere to provide the aimed food, which is, as necessary, packed with aluminum foil.