A receiving device includes a reception unit 10 that samples a signal to be measured a transmitted from a DUT 2 and acquires a sample signal d; an FFT processing unit 21 that performs an FFT process by multiplying the sample signal; a signal length calculation unit 31 that calculates a signal length of the signal to be measured from the sample signal; a comparing unit 33 that compares the calculated signal length of the signal to be measured with a first FFT length conforming to a communication standard; and an FFT length setting unit 34 that, when as a result of the comparison by the comparing unit, the signal length is shorter than the first FFT length, sets a second FFT length shorter than the signal length of the signal to be measured, as the FFT length of the FFT process by the FFT processing unit.