To provide a method of combining an impulse waveform which is used for an impulse response spectrum test and has a short time difference in appearing the impulse response spectrum.

In the impulse response spectrum test, the method of combining the impulse waveform, which has a short time difference for the appearance of the impulse response spectrum comprises a step of obtaining the time where the maximum value of the absolute value appear from a response content of one degree of freedom system having the same wavelet frequency to the natural frequency inputting a wavelet, consisting of a 0 delay time with respect the plural wavelets, having each different wavelet frequency; a step setting the value at which the time for appearing of the maximum value of the absolute value by the previous plural wavelets is subtracted from the longest time from among the times for appearing of the previous maximum value, as the previous delay time.