A polarization modulation imaging ellipsometer capable of measuring ellipsometric parameters of the surface of a sample for each of the measured points with high precision and at high speed, which has a light source unit that emits light whose intensity periodically changes at a predetermined frequency; an incident-light optical unit having a collimator, a polarizer, and a photoelastic phase modulator which modulates light emitted from the light source unit an emitted-light optical unit having an analyzer which analyzes a polarization state of light that has been reflected from or transmitted through the sample and a two-dimensional detector which converts light received from the analyzer to an electrical signal and outputs the electrical signal; and a control/analysis unit which operates the light source unit and the photoelastic phase modulator at the same frequency, and calculates ellipsometric parameters of each of the measured points.