In a spectroscopic ellipsometer (1), a lighting part (3) comprises a light source part for measurement (measurement light source) (31) and a polarizer (32), and the polarizer (32) obtains polarized light from light outputted from the measurement light source (31) and guides the polarized light to a substrate (9). A light receiving part (4) comprises an analyzer (41) on which reflected light which is the polarized light reflected on the substrate 9 is incident and a spectroscope (42), and the reflected light through the analyzer (41) enters the spectroscope (42), where a polarization state at each wavelength is acquired. The spectroscopic ellipsometer (1) has a construction in which mirrors are disposed only between the measurement light source (31) and the polarizer (32) and between the analyzer (41) and the spectroscope (42). In the spectroscopic ellipsometer (1), with this construction, the polarization state of the polarized light or its reflected light is not changed by mirrors and it is therefore possible to achieve measurements with high accuracy.