A .lambda./4 phase plate 821 is placed in an optical path between a blue light liquid crystal valve 811 and a cross-dichroic prism 813. S-polarized blue light incident on the blue Light liquid crystal light valve 811 is transmitted by an s-polarized light transmitting polarizer 811a without change, modulated by a liquid crystal panel 811b and a part thereof is converted into p-polarized light, and the p-polarized light is transmitted by a p-polarized light transmitting polarizer 811c to be emitted. The emitted p-polarized light is incident on the .lambda./4 phase plate and converted into circularly polarized light to be emitted, and is incident on the cross-dichroic prism 813. The circularly polarized light reflected from a red reflecting film 831 and a blue reflecting film 833 and incident on the .lambda./4 phase plate 821 again is converted into s-polarized light to be illuminated on the blue light liquid crystal valve 811, but is cut off by the p-polarized light transmitting polarizer 811c to prevent the influence on the liquid crystal panel 811b.