Chromatographs of a measurement target sample measured in FID and MS are displayed on display unit in a time range defined with reference to the retention index of the target component computed based on the standard retention time and calibration retention time for the target component in FID. The retention index is not readily influenced by difference in column length, thus making it possible to display the peaks of the target component measured with FID and MS in a corresponding time range by displaying the chromatograms on display unit in a time range defined with reference that retention index. Therefore, even in cases where the retention times of the target component in FID and MS are different, measurement results for an identical target component from FID and MS can be easily compared.