A difference between a peak reflectance of a first wavelength component and a reflectance of a second wavelength component having a predetermined wavelength among reflectances of a plurality of wavelength components constituting reflected light in a highlight direction from a glitter material-containing coating film is set as a first difference value. Reflectance is measured of the first and second wavelength components of the reflected light in the highlight direction for the coating film corresponding to a measurement object. A first difference value is calculated by using the measurement result. A storage stores in advance correlation information indicating a correlation between the first difference value and an index value indicating predetermined physical characteristics of a glitter material contained in the coating film. An index value calculator calculates the index value of the coating film corresponding to the measurement object by using the correlation information and the first difference value calculated in the first calculator.