A chromatographic analyzer is provided for facilitating curve fitting by means of the linear least-square method for a chromatogram that contains a plurality of overlapping peaks. The present invention is characterized by a chromatographic data processor for executing data processing of a chromatogram obtained by separating a sample to be measured using a column and detecting the separated sample, wherein fitting processing is executed to each peak in an arbitrary time region having the plurality of peaks of the chromatogram starting from the front side of the time region or from the back side of the time region, and the processed peaks are subtracted from the chromatogram in the time region so that the plurality of peaks in the chromatogram can be separated from one another. Thus, the plurality of overlapping peaks, particularly three or more overlapping peaks in the chromatogram can be easily separated from one another only by defining some setting conditions.