PURPOSE: To carry out the uniform and rapid thawing of frozen food, by the five-step thawing treatment comprising various combinations of the weight of the food, intensity of the high-frequency output, high-frequency irradiation time, and interval time.

CONSTITUTION: The weight of the frozen food, the standard irradiation period in the first step, and the irradiation coefficients per unit weight of the frozon food in the first, the third, and the fifth steps, are represented by Wg, t second, and K1, K3, and K5, respectively. The food is irradiated with high-frequency radiation at a high frequency output of 400W600W for T1 second (T1=t+K1W) in the first step, interrupted for T2 second (T2=1/2T1) in the second step, irradited at a high-frequency output of 150W250W for T3 second (T3=6t+K3W) in the third step, interrupted for T4 second (T4=1/2T3), and irradiated at an output of 90W150W for T5 second (T5=6t+K5W) in the fifth step.