A multivariate analysis operation unit (43) represents each of chromatogram data at a specific wavelength λ1 in data acquired by a PDA detector (2) and mass spectrum data repeatedly obtained by a mass spectrometer (3) in the form of a matrix, and then calculates a regression coefficient matrix by performing a PLS operation with a two-dimensional matrix based on the mass spectrum data as an explanatory variable and a one-dimensional matrix based on the chromatogram data as an explained variable. A regression coefficient is obtained with respect to each m/z value, and an m/z value having a high regression coefficient indicates an m/z value of which the chromatogram wavelength at a specific wavelength is similar to an extracted ion chromatogram (XIC). Accordingly, an m/z-value extracting unit (44) compares the regression coefficient with a threshold and extracts a significant m/z value, and an XIC creating unit (46) creates an XIC of the extracted m/z value. By specifying the wavelength λ1 that an operator's target partial chemical structure specifically absorbs, an XIC corresponding to a molecular species containing the partial chemical structure can be obtained without waveform processing manually performed by the operator.