A projection apparatus including a light source which generates light beams, an optical projection system which projects the light beams generated by the light source onto a screen, and a reflection device which is positioned between the light source and the optical projection system. The reflection device includes a plurality of mirrors capable of reflecting incident beams generated by the light source to travel toward the optical projection system. The projection apparatus also includes an optical illumination system which is positioned in an optical path between the light source and the reflection device and is tilted or decentered with respect to the optical axis of the light source to allow light beams generated by the light source to enter the reflection device at a predetermined angle. Since the optical paths of the optical projection system and the optical illumination system can be separated from each other by installing lenses in the optical illumination system, it is possible to manufacture the projection apparatus through a simple assembly and improve optical efficiency and a contrast ratio.