PROBLEM TO BE SOLVED: To measure a height of a measurement target surface of an object to be measured and a surface shape of the measurement target surface at high speed and with high accuracy on the basis of a comparatively small number of pieces of data.SOLUTION: A sampling interval for measuring an object to be measured 12 by a white interferometer device 1 is set, a specific part of a measurement target surface in the object to be measured 12 is imaged at the set sampling interval a plurality of times, image data obtained by the plurality of times of imaging are divided into an even data set of even-numbered image data and an odd data set of odd-numbered image data, density values of the specific part that is the measurement target surface in the object to be measured 12 are acquired from the respective even data set and odd data set to obtain modulation waves, the modulation waveform having higher contrast of them is selected, the selected modulation waveform is interpolated by the Fourier transform, and
