A color filter unit and a projection system employing the same. The color filter unit includes a first color selection polarization conversion element, which converts a polarization direction of a beam in a specific color band of an incident light, and a color filter, which separates light passed through the first color selection polarization conversion element according to color, so that color mixture in spectral boundaries between color beams is prevented. Because the color mixture occurring when beams into which light emitted from a white light source is separated are combined is prevented, the quality of an image is improved.