PURPOSE: To simulataneously measure Kerr ellipticity as well by including a magnetic field sweeping part which can sweep a magnetic field to a sample in a sample stage.
CONSTITUTION: Light 62 emitted from an output system 10 transmits the sample 20 in the magnetic field sweeping part 52 and arrives at a photodetecting system 14. The measurement of not only the reflected light from the sample 20 but the transmitted light of the transparent sample 20 as well is, therefore, possible. The measurement of the reflected light of the light from an exit optical system 10 by admitting the light at various angles to the sample 20 is possible as well. On the other hand, the adequate photodetection of the reflected light from the sample 20 is not possible unless a photodetecting system 14 is not rotated by an angle 2θ when the stage 12 is rotated by an angle θ in the mode for measuring the reflected light of the sample 20. The transmitted light or reflected light of the sample 20 is measured in the state of applying the magnetic field to the sample 20 in such a manner. The simultaneous measurement of the Kerr ellipticity by a function to measure elliptically polarized light is also possible.