For every acquisition of a set of mass spectrum data, a mass calibrator (determines the amount of mass discrepancy using the appearance position of a peak originating from an internal standard substance having a known m/z value, and performs a process for correcting the mass discrepancy. A mass calibration information collector (collects the amount of mass discrepancy or mass correction quantity for each set of mass spectrum data. After the completion of the measurement, a three-dimensional display information creator creates a three-dimensional graph showing the large number of collected mass correction quantities plotted in a three-dimensional space in which the retention time in a primary column and the retention time in a secondary column in a comprehensive two-dimensional LC unit are represented by two mutually orthogonal axes while the mass correction quantity is represented by the axis orthogonal to those two axes.