PURPOSE: To enable the extremely economical uniform thawing of frozen food, by irradiating the food with far infrared radiation having specific wavelength.

CONSTITUTION: Frozen food is thawed by irradiating with far infrared radiation of 5W50μ wavelength. Since the thawing can be carried out sufficiently by using a heat source of about 24kW power consumption, it is extremely economical compared with conventional process. The use of far infrared radiation of about 5W50μ wavelength enables the thawing from the inside of the frozen food with highest attainable uniformity keeping the taste and flavor of the food as far as possible. The thawing can be carried out hygienically, because the sundry germs attached to the frozen food can be completely exterminated by thawing.