A device includes a microwave generation unit that averages the first measured values and the second measured values at a predetermined movement average time and a predetermined sampling interval, and controls the microwave such that a value obtained by subtracting the averaged second measured value from the averaged first measured value comes close to the setting power, and in which the predetermined movement average time is 60 μs or less, and a relationship of y≥78.178x0.1775 is satisfied when the predetermined sampling interval is indicated by x, and the predetermined movement average time is indicated by y.