A spectroscopic ellipsometer can compare data different in a measurement condition and facilitate setting an initial value of fitting data even for an inexperienced operator such as a beginner. The spectroscopic ellipsometer includes a reference data storage part storing therein reference data to be compared with measurement data, a conversion operation part converting the measurement data or the reference data into comparable data, so that the measurement data can be compared with the reference data, and a comparison and determination part comparing the measurement data with the reference data made comparable by the conversion operation part with each other and determining a coincidence between the measurement data and the reference data.