Provided is a polarization measuring device including a stage on which a measurement target is provided, a light source assembly configured to emit incident light, a first polarimeter configured to polarize the incident light, a second polarimeter configured to polarize reflected light reflected from the measurement target that is irradiated by the incident light, a filter assembly configured to remove noise from the reflected light, and a detector configured to receive the reflected light and measure an intensity of the reflected light and a phase of the reflected light.