The operation efficiency and accuracy of the simultaneous analysis of phospholipids, including fatty acid compositions are increased. After a first-time LC/MS/MS analysis for determining the phospholipid classes of the phospholipid contained in a sample is performed (S2-S3), a second-time LC/MS/MS analysis for determining fatty acid compositions is performed only for the detected phospholipids (S4-S8). By associating a method list in which an MRM transition for phospholipid class determination is recorded for each compound of phospholipid classes with a method list in which an MRM transition for fatty acid composition determination is recorded for each phospholipid compound, it is possible to promptly select MRM transitions for fatty acid composition determination that correspond to compounds of the detected phospholipid classes, and to easily create an analysis method for the second-time analysis.