An exposure apparatus includes an illumination optical system for illuminating the reticle using the ultraviolet light from the light source, and a polarization measuring unit measuring the polarization state of the ultraviolet light, the polarization measuring unit including an optical unit for providing at least three different phase differences to the ultraviolet light that has passed at least part of the illumination optical system, a polarization element for providing a different transmittance in accordance with a polarization state of the ultraviolet light that has passed the optical unit, and an image pickup device for detecting a light intensity of the ultraviolet light that has passed the polarization element, the polarization measuring unit measuring the polarization state of the ultraviolet light that has passed the at least part of the illumination optical system based on a detection result of the image pickup device.