1. A method of calibrating a spectroscopic measurement instrument using a single test object, comprising: (a) acquiring, via software executing on a computer, observation data of a plurality of samples of the single test object from the spectroscopic measurement instrument; (b) acquiring, via software executing on the computer, content of a target component of each sample; (c) estimating, via software executing on the computer, a plurality of independent components when the observation data of each sample is separated into the plurality of independent components, and acquiring a mixing coefficient corresponding to the target component for each sample, based on the plurality of independent components; (d) acquiring, via software executing on the computer, a regression equation of a calibration curve based on the content of the target component of the plurality of samples and the mixing coefficient for each sample; and (e) calibrating the spectroscopic measurement instrument using the calibration curve, wherein (c) includes: (i) acquiring, via software executing on the computer, an independent component matrix including the independent component of each sample, (ii) acquiring, via software executing on the computer, an estimated mixing matrix showing a vector set for regulating a ratio of an independent component element of each independent component in each sample, from the independent component matrix, and (iii) acquiring, via software executing on the computer, a correlation of content of the target component of the plurality of samples, for each vector included in the estimated mixing matrix, and to select the vector which is determined to have a highest correlation, as a mixing coefficient corresponding to the target component, in (i), the computer acquires the independent component matrix by performing a first preprocessing including normalization of the observation data, a second preprocessing including whitening, and an independent component analysis process in this order, the computer uses β divergence as an independence index of the independent component analysis process, and a robust regression method is used in (d) acquiring the regression equation of the calibration curve.