The invention relates to a peak position correcting method that is a pre-process for testing whether properties of a product, a raw material, etc., are good or defective from a spectrum waveform pattern. The method involves setting a reference peak position in a single region including a spectrum waveform pattern, or setting reference peak positions in each of a plurality of regions; specifying a peak to be corrected as an object of correction in the single region or each of the plurality of regions; shifting the peak to be corrected to the reference peak position in the single region or in each of the plurality of regions; and substantially proportionally expanding or contracting the spectrum waveform pattern positioned at both sides of the peak to be corrected in the horizontal axis direction.