A surface profile measuring apparatus includes a reflection unit to reflect a reference beam diffracted by a first diffraction grating and cause the reflected reference beam to be incident on the first diffraction grating again, a detection unit to receive an interference beam in which the reference beam diffracted again by the first diffraction grating and a measuring beam reflected by a sample surface optically interfere with each other, and detect an interference intensity signal for each, wavelength in the interference beans, a shifting unit to shift the first diffraction grating in a direction perpendicular to a grating groove direction of the first diffraction grating, a calculation unit to calculates a phase on a basis of the interference intensity signal for each wavelength varying with a degree of shift, and a measurement unit to measure the sample surface.