A cross dichroic prism color-synthesizes a plurality of color lights having entered therein separately and emits color-synthesized light to a projection lens. The cross dichroic prism includes a first dichroic film; and a second dichroic film intersecting the first dichroic film so as to pass through the first dichroic film. The cross dichroic prism is configured so that a color light having entered the cross dichroic prism and having become diffracted at a gap created in the first dichroic film over an area where the second dichroic film passes through the first dichroic film is not projected through the projection lens.