Reflected light from the measurement object is received by a plurality of pixel columns arranged in an X2 direction in a light receiving unit 121, and a plurality of light receiving amount distributions is output. One or a plurality of peak candidate positions of light receiving amounts in a Z2 direction is detected by a peak detection unit 1 for each pixel column based on the plurality of light receiving amount distributions. A peak position to be adopted to a profile is selected from the peak candidate positions detected for each pixel column based on a relative positional relationship with a peak position of another pixel column adjacent to the pixel column, and profile data indicating the profile is generated by the profile generation unit 3 based on the selected peak position.