A method for testing a polarization state of polarized light includes forming a test photosensitive film on a test wafer, the test wafer having a flat surface and a grid pattern in which reflectance changes depending on a polarization direction of the polarized light, exposing the test photosensitive film to the polarized light, measuring a change of a property of the test photosensitive film caused by the polarized light, and determining a polarization state of the polarized light, based on the change.