Under-display fingerprint sensor of generating a fingerprint image disclosed. Under-display fingerprint sensor includes a light selection layer, being disposed under a display panel, configured for converting a downward circularly-polarized light into a downward linearly-polarized light, and configured for converting an unpolarized light into a sensor linearly-polarized light, a plurality of lenses, being disposed apart from the light selection layer and configured for refracting the downward linearly-polarized light and the sensor linearly-polarized light that propagate in a perpendicular direction toward each focal point, and an image sensor having a plurality of light receiving units disposed at each focal point of the plurality of lenses to receive the downward linearly-polarized light and the sensor linearly-polarized light that are refracted toward each focal point.