Data of a plurality of samples collected by an LC/MS, GC/MS or other systems are converted into a two-dimensional table format. After LC/MS measurement data on a plurality of samples are obtained and the respective extracted ion chromatograms (XICs) are created, a time-axis adjustment for correcting a discrepancy in the retention time is performed, followed by a process of correcting the missing of data which has occurred in the head and/or tail section of the data as a result of the time-axis adjustment.