An ellipsometer measures any point of a sample by a first spectrometer and a second spectrometer. The ellipsometer performs analysis based on the measurement results obtained by the first spectrometer, performs analysis based on the measurement results obtained by the second spectrometer, and calculates an approximation formula for approximating the analysis results obtained by the second spectrometer to the analysis results obtained by the first spectrometer. The remaining points of the sample are measured with the second spectrometer, and the results of analysis using the measurement results are corrected based on the approximation formula.