Reference data are subtracted from corresponding actual measurement data, and unprocessed binding quantity data, each of which represents a quantity of binding of a ligand and each of analytes, are thereby acquired. Calculation is made to find a relationship between the reference data and the unprocessed binding quantity data acquired in cases where the binding does not occur. In accordance with the relationship, variation components, which are contained in the unprocessed binding quantity data, are calculated. The variation components are subtracted from the corresponding unprocessed binding quantity data, and processed binding quantity data are thereby acquired. The processed binding quantity data are utilized for extracting an analyte capable of binding with the ligand.