There is provided a method of analyzing data obtained from an etching apparatus for micromachining a wafer using plasma. This method includes the following steps: acquiring the plasma light-emission data indicating light-emission intensities at a plurality of different wavelengths and times, the plasma light-emission data being measured under a plurality of different etching processing conditions, and being obtained at the time of the etching processing, evaluating the relationship between changes in the etching processing conditions and changes in the light-emission intensities at the plurality of different wavelengths and times with respect to the wavelengths and times of the plasma light-emission data, and identifying the wavelength and the time of the plasma light-emission data based on the evaluation result, the wavelength and the time being to be used for the adjustment of the etching processing condition.