A peak extraction method for extracting a true peak from a measured waveform, including acquiring a second derivative waveform; extracting a provisional peak on the basis of a maximum value and/or a minimum value of the second derivative waveform; determining the peak width of the provisional peak on the basis of a model peak function; computing, on the basis of the model peak function, a theoretical value for the height of the provisional peak using two points corresponding to the two ends of the peak width; computing, based on the second derivative waveform, an index value for a variation in the noise on the measured waveform; and computing an S/N ratio, which is a ratio of the peak height theoretical value and the index value, and extracting the provisional peak that is equal to or greater than a preset value as the true peak.