Liquid crystal modulation elements are arranged so that light outgoing surfaces thereof face light incident surfaces of a color synthesizing prism. Transparent plates are bonded to the light outgoing surfaces of the liquid crystal modulation elements. For this reason, adhesion of dust to the light outgoing surfaces of the liquid crystal modulation elements can be prevented. Further, it is possible to prevent light reflection at the interface surface between the light outgoing surfaces and air due to the difference in refractive index therebetween. This allows a high-quality image to be projected without deteriorating the switching characteristic of the liquid crystal modulation elements while preventing dust from adhering to the light outgoing surfaces of the liquid crystal modulation elements.