A method and a system for evaluating results of differentiating genotype signals and noise signals when a DNA fragment containing a gene to be analyzed is amplified by PCR and detected by electrophoresis are provided. An outlier of genotyping results is detected based on the fact that, when using the same marker, the height ratio of a stutter peak to a true peak and the height ratio of a +A peak to a true peak are reproducible, and that a constant size value is obtained with the use of the same allele of the same marker. In addition, a waveform obtained in past processes with the use of the same marker or the same allele is obtained utilizing a database by focusing on reproducibility. Also, a database is extended so as to obtain improved evaluation ability in a manner such that appropriate waveform data from which an outlier is not obtained is additionally registered in a database.