Abstract: A prism system is utilized in tricolor separation in order to obtain three images of separated colors by passing through the prism a light beam from a single objective lens system. The prism system includes first, second and third prisms, each having the same refractive index. First and second interference filters are utilized in conjunction with the prisms in order to provide reflecting lights and transmitted lights that are complementary to each other. The first prism is a right-angled triangular prism having a vertical angle of 30.degree., with its oblique surface being disposed at a right angle to the optical axis of the objective lens system. The second and third prisms are each of a trapezoidal shape, having the identical size. Two adjoining angles of the trapezoidal prisms are 90.degree. and the other two angles are 60.degree. and 120.degree., respectively as viewed in their cross sections.