An ellipsometer includes a first separation unit configured to separate a first reflected light into two reflected lights, a first polarizing optical element configured to separate each of the two reflected lights into two linearly polarized lights, a first interference device configured to form an interference fringe by allowing components of the two linearly polarized lights to interfere with each other, a second separation unit configured to separate a second reflected light into two reflected lights, a second polarizing optical element configured to separate each of the two reflected lights into two linearly polarized lights, and a second interference device configured to form an interference fringe by allowing components of the two linearly polarized lights to interfere with each other.